PRACK

PRACK: We all know what is a response for a request. Here is a method in SIP which is a request for a response.

Sometimes provisional response needs reliability on transport. And SIP goes over UDP which is unreliable. So SIP introduces a method for Provisional Response reliability that is Provisional Response ACK. It works in a 3 way handshake mechanism. A provisional response is acked by PRACK which is replied with 200 Ok.

A PRACK can be used by UAC when the UAS sends a Provisional Response (1xx). Exception is 100 Trying. But such a PRACK request should be sent only if the provisional response has 100rel extension (100 reliability) in supported or required header field.


If UAS definitely require 100rel extension for call processing but is not listed in the supported header of INVITE / Request, UAS can terminate the call with 421 Extension required error message.

If UAC feels it does not knows 100rel extension sent in provisional response, it can reject the main request (Invite etc) with 420 Bad request.

The PRACK is an end-to-end request. Proxy does not have any dependancies on Provisional responses. They simply forward 1xx response. The only exception is 100 trying, which is hop to hop response. Hence the PRACK is not used for 100 trying alone.

Following are the headers which plays its role in decoding PRACK.
RSeq - Remote sequence number. The UAC will insert this number (random start value for security purpose) when it requires PRACK in the provisional response.
RAck - This header used in the PRACK request. Formed by combining the RSeq number, CSeq number, CSeq method of the provisional response.
Other than these two, CSeq, From, To, Call-ID all play their part as usual.

The provisional response is retransmitted as long as it gets a PRACK but within 4 secs. It first starts with 500ms (T1) and retransmitted in exponential backoff. Similarly the PRACK is retransmitted as long as UAC's 200 Ok reaches UAS.

Client transaction - Invite State Machine

RFC 3261 specifies the client transaction state machines that SIP uses in its section 17.

Client transaction - Invite State Machine:

This section explains the Client transaction state machine for Invite. State machine has 4 states: Calling Proceeding, Completed, Terminated. This state machine uses 3 way handshake mechanisms.

Timers used

Timer T1:

- Purpose: Round Trip Time

- Default Value: 500 ms

Timer A:

- Controls retransmissions of client transaction.

- Default Value: set to T1

- Uses exponential backoff. 2* T1, 4* T1

Timer B:

- Controls Timeout of client transaction.

- Default Value: set to 64*T1

Timer D:

- Reference to Timer H at client transaction.

- Default Value: 32s

Timer H:

- Amount of time server transaction can remain in ‘COMPLETED’ state

- Default value: 64 * T1 (Server transaction’s Timer T1)

STATE - CALLING:

• This state is entered when UAC core creates a client transaction for sending INVITE outside the dialog.
• On entering CALLING state, TIMER B is set to 64 * T1.
• TIMER A is set to T1 in case the transport to be used is unreliable (UDP). Incase of reliable transport, TIMER A is not used.
• In case TIMER A fires when the client transaction is still in CALLING state, retransmission of INVITE would happen and TIMER A would be resetted to exponential back off (2*T1, 4*T1..)
• In case TIMER B fires when client transaction is in CALLING state, UA should be intimated about the timeout and Client transaction state would be changed to TERMINIATED. No ACK should be generated.
• If response from server transaction is 1xx, the response is sent to Transaction user, then the client transaction enters PROCEEDING STATE.
• If response from server transaction is 2xx, the response is sent to Transaction user, then the client transaction enters TERMINATED STATE.
• If response from server transaction is 3xx to 6xx, the response is sent to Transaction user, then the client transaction enters COMPLETED state and it should generate ACK.

STATE – PROCEEDING:

• Request should not be retransmitted any longer when in PROCEEDING state
• TIMERS have no effect on this state
• If response from server transaction is 1xx, the response is sent to Transaction user and the client transaction remains at PROCEEDING state.
• If response from server transaction is 2xx, the response is sent to Transaction user, then the client transaction enters TERMINATED STATE.
• If response from server transaction is 3xx to 6xx, the response is sent to Transaction user, then the client transaction enters COMPLETED state and it should generate ACK.

STATE – COMPLETED:

• Once client transaction enters COMPLETED state, which happens when server transaction sends any response of 3xx – 6xx, TIMER D should be started.
• For reliable transport it is 0 and for unreliable transport it is equal to TIMER H of server transaction which is 64 * T1. Since we don’t know the T1 of the server transaction, we set it to 32s as absolute minimum.
• Any retransmission of final response should not be passed to Transaction user. Instead, client transaction should generate ACK and send it to Transport layer.
• Once the TIMER D fires, the transaction is moved immediately to TERMINATED state.

STATE – TERMINATED:

• Client transaction enters this state, if 2xx response is received by it in either CALLING or PROCEEDING state or a timeout has occurred.
• Handling a 2xx response depends on the type of UAC. This is the reason the transaction layer does not handle 2xx response. The 2xx response is passed on to Transaction User.
• Client transaction will be destroyed immediately on entering TERMINATED state.

Any response that the client transaction receives that does not matches any ongoing transaction, then the response is directly passed on to the Transaction User. On receipt of first 2xx response, the client transaction is terminated. Hence the subsequent 2xx responses would be directly sent to UAC core.

Simple Call Flow B2BUA

I have set up an Asterisk with Fedora Core 14. Has two virtual machines running with Sun Virtual Box running XP with bridged ethernet. Each has a xlite phone. Tried to create a basic call flow and here is the output.

IP Address:
Asterisk Server : 192.168.1.2
Virtual Mach 1 : 192.168.1.3
Virtual Mach 2 : 192.168.1.4

Extensions:
*CLI&~~SPECIAL_REMOVE!#~~gt; sip show peers
Name/username Host Dyn Forcerport ACL Port Status
6000/6000 192.168.1.4 D N 10988 Unmonitored
6001/6001 192.168.1.3 D N 50690 Unmonitored
2 sip peers [Monitored: 0 online, 0 offline Unmonitored: 2 online, 0 offline]
*CLI&~~SPECIAL_REMOVE!#~~gt;

Description:
- Add two SIP endpoints to Asterisk.
- Make a call from 6001 to 6000
- Disconnect the call from 6000.

Call Flow [Wireshark]:

SIP Messages and Observations:

1. Invite [8.956]: [Caller to Asterisk]

INVITE sip:6000@192.168.1.2 SIP/2.0

Via: SIP/2.0/UDP 192.168.1.3:19048;branch=z9hG4bK-d8754z-e13ddd965409862f-1---d8754z-;rport

Max-Forwards: 70

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.3:19048&~~SPECIAL_REMOVE!#~~gt;

To: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;

From: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=ba82e016

Call-ID: Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.

CSeq: 1 INVITE

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY, MESSAGE, SUBSCRIBE, INFO

Content-Type: application/sdp

Supported: replaces

User-Agent: X-Lite 4 release 4.0 stamp 58832

Content-Length: 402

v=0

o=- 12938412643424210 1 IN IP4 192.168.1.3

s=CounterPath X-Lite 4.0

c=IN IP4 192.168.1.3

t=0 0

a=ice-ufrag:692c3c

a=ice-pwd:4c8da4ea941b5b1164acc5b44e5918ce

m=audio 64356 RTP/AVP 107 0 8 101

a=rtpmap:107 BV32/16000

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-15

a=sendrecv

a=candidate:1 1 UDP 659136 192.168.1.3 64356 typ host

a=candidate:1 2 UDP 659134 192.168.1.3 64357 typ host

Message Direction [Network]
From	192.168.1.3 [6001]
To	192.168.1.2 [Asterisk]

Dialog: [Dialog ID]
Call ID	Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.
Local Tag	ba82e016
Remote Tag	-
Dialog initiated?	NO
Transaction
Branch Parameters of Via	z9hG4bK-d8754z-e13ddd965409862f-1---d8754z-
Cseq	1 INVITE

Session Parameters [SDP]
Session ID	12938412643424210	Session Version	1
Message From	192.168.1.3	Message To	192.168.1.2
Codecs	PCMU[0], PCMA[8]	Target RTP To	192.168.1.3: 64356
Start Time	0	End Time	0

2. 100 Trying [8.957]: From Asterisk to Caller [6001]

SIP/2.0 100 Trying

Via: SIP/2.0/UDP 192.168.1.3:19048;branch=z9hG4bK-d8754z-e13ddd965409862f-1---d8754z-;received=192.168.1.3;rport=19048

From: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=ba82e016

To: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;

Call-ID: Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.

CSeq: 1 INVITE

Server: Asterisk PBX SVN-trunk-r300045

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH

Supported: replaces, timer

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2:5060&~~SPECIAL_REMOVE!#~~gt;

Content-Length: 0

Message Direction [Network]
From	192.168.1.2 [Asterisk]
To	192.168.1.3 [6001]

Dialog: [Dialog ID]
Call ID	Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.
Local Tag	-
Remote Tag	ba82e016
Dialog initiated?	NO
Transaction
Branch Parameters of Via	z9hG4bK-d8754z-e13ddd965409862f-1---d8754z-
Cseq	1 INVITE

3. Invite [8.958]: Asterisk to Called [6000@192.168.1.4]

INVITE sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26 SIP/2.0

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK13e1b485;rport

Max-Forwards: 70

From: "Balakrishnan" &~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as6f235314

To: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26&~~SPECIAL_REMOVE!#~~gt;

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2:5060&~~SPECIAL_REMOVE!#~~gt;

Call-ID: 08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060

CSeq: 102 INVITE

User-Agent: Asterisk PBX SVN-trunk-r300045

Date: Sun, 02 Jan 2011 03:30:38 GMT

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH

Supported: replaces, timer

Content-Type: application/sdp

Content-Length: 294

v=0

o=root 1341205026 1341205026 IN IP4 192.168.1.2

s=Asterisk PBX SVN-trunk-r300045

c=IN IP4 192.168.1.2

t=0 0

m=audio 14726 RTP/AVP 0 3 101

a=rtpmap:0 PCMU/8000

a=rtpmap:3 GSM/8000

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-16

a=silenceSupp:off - - - -

a=ptime:20

a=sendrecv

Message Direction [Network]
From	192.168.1.2 [Asterisk]
To	192.168.1.4 [6000]
Dialog: [Dialog ID]
Call ID	08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060
Local Tag	as6f235314
Remote Tag	-
Dialog initiated?	NO
Transaction
Branch Parameters of Via	z9hG4bK13e1b485
Cseq	102 INVITE

Session Parameters [SDP]
Session ID	1341205026	Session Version	1341205026
Message From	192.168.1.2	Message To	192.168.1.4
Codecs	PCMU[0], GSM6.10[3]	Target RTP To	192.168.1.2:14726
Start Time	0	End Time	0

4. 100 Trying [Called to Asterisk]

SIP/2.0 100 Trying

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK13e1b485;rport=5060

To: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26&~~SPECIAL_REMOVE!#~~gt;

From: "Balakrishnan" &~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as6f235314

Call-ID: 08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060

CSeq: 102 INVITE

Content-Length: 0

Message Direction [Network]
From	192.168.1.4 [6000]
To	192.168.1.2 [Asterisk]
Dialog: [Dialog ID]
Call ID	08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060
Local Tag	-
Remote Tag	as6f235314
Dialog initiated?	NO
Transaction
Branch Parameters of Via	z9hG4bK13e1b485
Cseq	102 INVITE

5. 180 Ringing [Called to Asterisk]

SIP/2.0 180 Ringing

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK13e1b485;rport=5060

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26&~~SPECIAL_REMOVE!#~~gt;

To: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26&~~SPECIAL_REMOVE!#~~gt;;tag=73907587

From: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as6f235314

Call-ID: 08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060

CSeq: 102 INVITE

User-Agent: X-Lite 4 release 4.0 stamp 58832

Content-Length: 0

Message Direction [Network]
From	192.168.1.4 [6000]
To	192.168.1.2 [Asterisk]
Dialog: [Dialog ID]
Call ID	08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060
Local Tag	73907587
Remote Tag	as6f235314
Dialog initiated?	Early Dialog
Dialog [Parameters]
Local Seq No	-
Remote Seq No	102 Invite
Local URI	sip:6000@192.168.1.4
Remote URI	sip:6001@192.168.1.2
Remote Target	sip:6001@192.168.1.2:5060
Secure Flag	N
Route Set	192.168.1.2:5060
Transaction
Branch Parameters of Via	z9hG4bK13e1b485
Cseq	102 INVITE

6. 180 Ringing [Asterisk to Caller]

SIP/2.0 180 Ringing

Via: SIP/2.0/UDP 192.168.1.3:19048;branch=z9hG4bK-d8754z-e13ddd965409862f-1---d8754z-;received=192.168.1.3;rport=19048

From: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=ba82e016

To: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as0ac5182d

Call-ID: Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.

CSeq: 1 INVITE

Server: Asterisk PBX SVN-trunk-r300045

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH

Supported: replaces, timer

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2:5060&~~SPECIAL_REMOVE!#~~gt;

Content-Length: 0

Message Direction [Network]
From	192.168.1.2 [Asterisk]
To	192.168.1.3 [6001]

Dialog: [Dialog ID]
Call ID	Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.
Local Tag	as0ac5182d
Remote Tag	ba82e016
Dialog initiated?	Early Dialog
Dialog [Parameters]
Local Seq No	-
Remote Seq No	1 INVITE
Local URI	sip:6000@192.168.1.2
Remote URI	sip:6001@192.168.1.2
Remote Target	sip:6001@192.168.1.3:19048
Secure Flag	N
Route Set	192.168.1.3:19048
Transaction
Branch Parameters of Via	z9hG4bK-d8754z-e13ddd965409862f-1---d8754z-
Cseq	1 INVITE

7. 200 OK [Called to Asterisk]:

SIP/2.0 200 OK

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK13e1b485;rport=5060

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26&~~SPECIAL_REMOVE!#~~gt;

To: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26&~~SPECIAL_REMOVE!#~~gt;;tag=73907587

From: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as6f235314

Call-ID: 08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060

CSeq: 102 INVITE

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY, MESSAGE, SUBSCRIBE, INFO

Content-Type: application/sdp

Supported: replaces

User-Agent: X-Lite 4 release 4.0 stamp 58832

Content-Length: 371

v=0

o=- 12938412641879229 1 IN IP4 192.168.1.4

s=CounterPath X-Lite 4.0

c=IN IP4 192.168.1.4

t=0 0

a=ice-ufrag:4e8652

a=ice-pwd:ba7d4da3686f1e7c6c530f3c773ae3e7

m=audio 62964 RTP/AVP 0 101

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-15

a=sendrecv

a=candidate:1 1 UDP 659136 192.168.1.4 62964 typ host

a=candidate:1 2 UDP 659134 192.168.1.4 62965 typ host

Message Direction [Network]
From	192.168.1.4 [6000]
To	192.168.1.2 [Asterisk]
Dialog: [Dialog ID]
Call ID	08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060
Local Tag	73907587
Remote Tag	as6f235314
Dialog initiated?	Established
Dialog [Parameters]
Local Seq No	-
Remote Seq No	102 Invite
Local URI	sip:6000@192.168.1.4
Remote URI	sip:6001@192.168.1.2
Remote Target	sip:6001@192.168.1.2:5060
Secure Flag	N
Route Set	192.168.1.2:5060
Transaction
Branch Parameters of Via	z9hG4bK13e1b485
Cseq	102 INVITE

Session Parameters [SDP]
Session ID	12938412641879229	Session Version	1
Message From	192.168.1.4	Message To	192.168.1.2
Codecs	PCMU[0]	Target RTP To	192.168.1.4:62964
Start Time	0	End Time	0

RTP transfer happens between 192.168.1.2:14726 and 192.168.1.4:62964 [Asterisk to Called]

8. ACK [Asterisk to Called]:

ACK sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26 SIP/2.0

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK3571b83f;rport

Max-Forwards: 70

From: "Balakrishnan" &~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as6f235314

To: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26&~~SPECIAL_REMOVE!#~~gt;;tag=73907587

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2:5060&~~SPECIAL_REMOVE!#~~gt;

Call-ID: 08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060

CSeq: 102 ACK

User-Agent: Asterisk PBX SVN-trunk-r300045

Content-Length: 0

Message Direction [Network]
From	192.168.1.2 [Asterisk]
To	192.168.1.4 [6000]
Dialog: [Dialog ID]
Call ID	08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060
Local Tag	as6f235314
Remote Tag	73907587
Dialog initiated?	Established
Dialog [Parameters]
Local Seq No	102 ACK
Remote Seq No	-
Local URI	sip:6001@192.168.1.2
Remote URI	sip:6000@192.168.1.4
Remote Target	sip:6000@192.168.1.4:23718
Secure Flag	N
Route Set	192.168.1.2:5060
Transaction
Branch Parameters of Via	z9hG4bK3571b83f
Cseq	102 ACK

9. 200 OK [Asterisk to Caller]

SIP/2.0 200 OK

Via: SIP/2.0/UDP 192.168.1.3:19048;branch=z9hG4bK-d8754z-e13ddd965409862f-1---d8754z-;received=192.168.1.3;rport=19048

From: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=ba82e016

To: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as0ac5182d

Call-ID: Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.

CSeq: 1 INVITE

Server: Asterisk PBX SVN-trunk-r300045

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH

Supported: replaces, timer

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2:5060&~~SPECIAL_REMOVE!#~~gt;

Content-Type: application/sdp

Content-Length: 271

v=0

o=root 1277759869 1277759869 IN IP4 192.168.1.2

s=Asterisk PBX SVN-trunk-r300045

c=IN IP4 192.168.1.2

t=0 0

m=audio 12832 RTP/AVP 0 101

a=rtpmap:0 PCMU/8000

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-16

a=silenceSupp:off - - - -

a=ptime:20

a=sendrecv

Message Direction [Network]
From	192.168.1.2 [Asterisk]
To	192.168.1.3 [6001]

Dialog: [Dialog ID]
Call ID	Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.
Local Tag	as0ac5182d
Remote Tag	ba82e016
Dialog initiated?	Established
Dialog [Parameters]
Local Seq No	-
Remote Seq No	1 INVITE
Local URI	sip:6000@192.168.1.2
Remote URI	sip:6001@192.168.1.2
Remote Target	sip:6001@192.168.1.3:19048
Secure Flag	N
Route Set	192.168.1.3:19048
Transaction
Branch Parameters of Via	z9hG4bK-d8754z-e13ddd965409862f-1---d8754z-
Cseq	1 INVITE

Session Parameters [SDP]
Session ID	1277759869	Session Version	1277759869
Message From	192.168.1.2	Message To	192.168.1.3
Codecs	PCMU[0]	Target RTP To	192.168.1.2:12832
Start Time	0	End Time	0

RTP Transfer happens between 192.168.1.3:64356 and 192.168.1.2:12832 [Caller and Asterisk]

10. Invite [Asterisk to Called]

INVITE sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26 SIP/2.0

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK4a7b08c0;rport

Max-Forwards: 70

From: "Balakrishnan" &~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as6f235314

To: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26&~~SPECIAL_REMOVE!#~~gt;;tag=73907587

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2:5060&~~SPECIAL_REMOVE!#~~gt;

Call-ID: 08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060

CSeq: 103 INVITE

User-Agent: Asterisk PBX SVN-trunk-r300045

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH

Supported: replaces, timer

Content-Type: application/sdp

Content-Length: 271

v=0

o=root 1341205026 1341205027 IN IP4 192.168.1.3

s=Asterisk PBX SVN-trunk-r300045

c=IN IP4 192.168.1.3

t=0 0

m=audio 64356 RTP/AVP 0 101

a=rtpmap:0 PCMU/8000

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-16

a=silenceSupp:off - - - -

a=ptime:20

a=sendrecv

Message Direction [Network]
From	192.168.1.2 [Asterisk]
To	192.168.1.4 [6000]
Dialog: [Dialog ID]
Call ID	08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060
Local Tag	as6f235314
Remote Tag	73907587
Dialog initiated?	Established
Dialog [Parameters]
Local Seq No	103 INVITE
Remote Seq No	-
Local URI	sip:6001@192.168.1.2
Remote URI	sip:6000@192.168.1.4:23718
Remote Target	sip:6000@192.168.1.4:23718
Secure Flag	N
Route Set	192.168.1.2:5060
Transaction
Branch Parameters of Via	z9hG4bK4a7b08c0
Cseq	103 INVITE

Session Parameters [SDP]
Session ID	1341205026	Session Version	1341205027
Message From	192.168.1.2	Message To	192.168.1.4
Codecs	PCMU[0]	Target RTP To	192.168.1.3:64356
Start Time	0	End Time	0

11. 200 OK [Called to Asterisk]

SIP/2.0 200 OK

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK4a7b08c0;rport=5060

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26&~~SPECIAL_REMOVE!#~~gt;

To: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26&~~SPECIAL_REMOVE!#~~gt;;tag=73907587

From: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as6f235314

Call-ID: 08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060

CSeq: 103 INVITE

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY, MESSAGE, SUBSCRIBE, INFO

Content-Type: application/sdp

Supported: replaces

User-Agent: X-Lite 4 release 4.0 stamp 58832

Content-Length: 371

v=0

o=- 12938412641879229 2 IN IP4 192.168.1.4

s=CounterPath X-Lite 4.0

c=IN IP4 192.168.1.4

t=0 0

a=ice-ufrag:4e8652

a=ice-pwd:ba7d4da3686f1e7c6c530f3c773ae3e7

m=audio 62964 RTP/AVP 0 101

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-15

a=sendrecv

a=candidate:1 1 UDP 659136 192.168.1.4 62964 typ host

a=candidate:1 2 UDP 659134 192.168.1.4 62965 typ host

Message Direction [Network]
From	192.168.1.4 [6000]
To	192.168.1.2 [Asterisk]
Dialog: [Dialog ID]
Call ID	08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060
Local Tag	73907587
Remote Tag	as6f235314
Dialog initiated?	Established
Dialog [Parameters]
Local Seq No	-
Remote Seq No	103 INVITE
Local URI	Sip:6000@192.168.1.4:23718
Remote URI	sip:6001@192.168.1.2
Remote Target	sip:6001@192.168.1.2:5060
Secure Flag	N
Route Set	192.168.1.2:5060
Transaction
Branch Parameters of Via	z9hG4bK4a7b08c0
Cseq	103 INVITE

Session Parameters [SDP]
Session ID	12938412641879229	Session Version	2
Message From	192.168.1.4	Message To	192.168.1.2
Codecs	PCMU[0]	Target RTP To	192.168.1.4:62964
Start Time	0	End Time	0

12. ACK [Asterisk to Called]

ACK sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26 SIP/2.0

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK34b97262;rport

Max-Forwards: 70

From: "Balakrishnan" &~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as6f235314

To: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26&~~SPECIAL_REMOVE!#~~gt;;tag=73907587

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2:5060&~~SPECIAL_REMOVE!#~~gt;

Call-ID: 08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060

CSeq: 103 ACK

User-Agent: Asterisk PBX SVN-trunk-r300045

Content-Length: 0

Message Direction [Network]
From	192.168.1.2 [Asterisk]
To	192.168.1.4 [6000]
Dialog: [Dialog ID]
Call ID	08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060
Local Tag	as6f235314
Remote Tag	73907587
Dialog initiated?	Established
Dialog [Parameters]
Local Seq No	103 ACK
Remote Seq No	-
Local URI	sip:6001@192.168.1.2
Remote URI	sip:6000@192.168.1.4:23718
Remote Target	sip:6000@192.168.1.4:23718
Secure Flag	N
Route Set	192.168.1.2:5060
Transaction
Branch Parameters of Via	z9hG4bK34b97262
Cseq	103 ACK

13. ACK [Caller to Asterisk]

ACK sip:6000@192.168.1.2:5060 SIP/2.0

Via: SIP/2.0/UDP 192.168.1.3:19048;branch=z9hG4bK-d8754z-09f35202913428c0-1---d8754z-;rport

Max-Forwards: 70

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.3:19048&~~SPECIAL_REMOVE!#~~gt;

To: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as0ac5182d

From: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=ba82e016

Call-ID: Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.

CSeq: 1 ACK

User-Agent: X-Lite 4 release 4.0 stamp 58832

Content-Length: 0

Message Direction [Network]
From	192.168.1.3 [6001]
To	192.168.1.2 [Asterisk]

Dialog: [Dialog ID]
Call ID	Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.
Local Tag	ba82e016
Remote Tag	as0ac5182d
Dialog initiated?	Established
Dialog [Parameters]
Local Seq No	1 ACK
Remote Seq No	-
Local URI	sip:6001@192.168.1.2
Remote URI	sip:6000@192.168.1.2
Remote Target	sip:6000@192.168.1.2:5060
Secure Flag	N
Route Set	192.168.1.3:19048
Transaction
Branch Parameters of Via	z9hG4bK-d8754z-09f35202913428c0-1---d8754z
Cseq	1 ACK

14. Invite [Asterisk to Caller]

INVITE sip:6001@192.168.1.3:19048 SIP/2.0

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK6c1d9407;rport

Max-Forwards: 70

From: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as0ac5182d

To: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=ba82e016

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2:5060&~~SPECIAL_REMOVE!#~~gt;

Call-ID: Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.

CSeq: 102 INVITE

User-Agent: Asterisk PBX SVN-trunk-r300045

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH

Supported: replaces, timer

Content-Type: application/sdp

Content-Length: 271

v=0

o=root 1277759869 1277759870 IN IP4 192.168.1.4

s=Asterisk PBX SVN-trunk-r300045

c=IN IP4 192.168.1.4

t=0 0

m=audio 62964 RTP/AVP 0 101

a=rtpmap:0 PCMU/8000

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-16

a=silenceSupp:off - - - -

a=ptime:20

a=sendrecv

Message Direction [Network]
From	192.168.1.2 [Asterisk]
To	192.168.1.3 [6001]

Dialog: [Dialog ID]
Call ID	Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.
Local Tag	as0ac5182d
Remote Tag	ba82e016
Dialog initiated?	Established
Dialog [Parameters]
Local Seq No	102 INVITE
Remote Seq No	-
Local URI	sip:6000@192.168.1.2
Remote URI	sip:6001@192.168.1.2
Remote Target	sip:6001@192.168.1.3:19048
Secure Flag	N
Route Set	192.168.1.2:5060
Transaction
Branch Parameters of Via	z9hG4bK6c1d9407
Cseq	102 INVITE

Session Parameters [SDP]
Session ID	1277759869	Session Version	1277759870
Message From	192.168.1.2	Message To	192.168.1.3
Codecs	PCMU[0]	Target RTP To	192.168.1.4:62964
Start Time	0	End Time	0

15. 200 OK [ Caller to Asterisk]

SIP/2.0 200 OK

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK6c1d9407;rport=5060

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.3:19048&~~SPECIAL_REMOVE!#~~gt;

To: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=ba82e016

From: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as0ac5182d

Call-ID: Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.

CSeq: 102 INVITE

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY, MESSAGE, SUBSCRIBE, INFO

Content-Type: application/sdp

Supported: replaces

User-Agent: X-Lite 4 release 4.0 stamp 58832

Content-Length: 371

v=0

o=- 12938412643424210 2 IN IP4 192.168.1.3

s=CounterPath X-Lite 4.0

c=IN IP4 192.168.1.3

t=0 0

a=ice-ufrag:692c3c

a=ice-pwd:4c8da4ea941b5b1164acc5b44e5918ce

m=audio 64356 RTP/AVP 0 101

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-15

a=sendrecv

a=candidate:1 1 UDP 659136 192.168.1.3 64356 typ host

a=candidate:1 2 UDP 659134 192.168.1.3 64357 typ host

Message Direction [Network]
From	192.168.1.3 [6001]
To	192.168.1.2 [Asterisk]

Dialog: [Dialog ID]
Call ID	Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.
Local Tag	ba82e016
Remote Tag	as0ac5182d
Dialog initiated?	Established
Dialog [Parameters]
Local Seq No	-
Remote Seq No	102 INVITE
Local URI	sip:6001@192.168.1.2
Remote URI	sip:6000@192.168.1.2
Remote Target	sip:6000@192.168.1.2:5060
Secure Flag	N
Route Set	192.168.1.3:19048
Transaction
Branch Parameters of Via	z9hG4bK-d8754z-09f35202913428c0-1---d8754z
Cseq	1 ACK

Session Parameters [SDP]
Session ID	12938412643424210	Session Version	2
Message From	192.168.1.3	Message To	192.168.1.2
Codecs	PCMU[0]	Target RTP To	192.168.1.3:64356
Start Time	0	End Time	0

16. ACK [Asterisk to Caller]

ACK sip:6001@192.168.1.3:19048 SIP/2.0

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK6aa9862b;rport

Max-Forwards: 70

From: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as0ac5182d

To: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=ba82e016

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2:5060&~~SPECIAL_REMOVE!#~~gt;

Call-ID: Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.

CSeq: 102 ACK

User-Agent: Asterisk PBX SVN-trunk-r300045

Content-Length: 0

Message Direction [Network]
From	192.168.1.2 [Asterisk]
To	192.168.1.3 [6001]

Dialog: [Dialog ID]
Call ID	Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.
Local Tag	as0ac5182d
Remote Tag	ba82e016
Dialog initiated?	Established
Dialog [Parameters]
Local Seq No	102 ACK
Remote Seq No	-
Local URI	sip:6000@192.168.1.2
Remote URI	sip:6001@192.168.1.2
Remote Target	sip:6001@192.168.1.3:19048
Secure Flag	N
Route Set	192.168.1.2:5060
Transaction
Branch Parameters of Via	z9hG4bK6aa9862b
Cseq	102 ACK

17. Invite [Asterisk to Called]

INVITE sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26 SIP/2.0

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK4fc5ca1e;rport

Max-Forwards: 70

From: "Balakrishnan" &~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as6f235314

To: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26&~~SPECIAL_REMOVE!#~~gt;;tag=73907587

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2:5060&~~SPECIAL_REMOVE!#~~gt;

Call-ID: 08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060

CSeq: 104 INVITE

User-Agent: Asterisk PBX SVN-trunk-r300045

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH

Supported: replaces, timer

Content-Type: application/sdp

Content-Length: 271

v=0

o=root 1341205026 1341205028 IN IP4 192.168.1.3

s=Asterisk PBX SVN-trunk-r300045

c=IN IP4 192.168.1.3

t=0 0

m=audio 64356 RTP/AVP 0 101

a=rtpmap:0 PCMU/8000

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-16

a=silenceSupp:off - - - -

a=ptime:20

a=sendrecv

Message Direction [Network]
From	192.168.1.2 [Asterisk]
To	192.168.1.4 [6000]
Dialog: [Dialog ID]
Call ID	08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060
Local Tag	as6f235314
Remote Tag	73907587
Dialog initiated?	Established
Dialog [Parameters]
Local Seq No	104 INVITE
Remote Seq No	-
Local URI	sip:6001@192.168.1.2
Remote URI	sip:6000@192.168.1.4:23718
Remote Target	sip:6000@192.168.1.4:23718
Secure Flag	N
Route Set	192.168.1.2:5060
Transaction
Branch Parameters of Via	z9hG4bK4fc5ca1e
Cseq	104 INVITE

Session Parameters [SDP]
Session ID	1341205026	Session Version	1341205028
Message From	192.168.1.2	Message To	192.168.1.4
Codecs	PCMU[0]	Target RTP To	192.168.1.3:64356
Start Time	0	End Time	0

18. 200 OK [Called to Asterisk]

SIP/2.0 200 OK

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK4fc5ca1e;rport=5060

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26&~~SPECIAL_REMOVE!#~~gt;

To: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26&~~SPECIAL_REMOVE!#~~gt;;tag=73907587

From: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as6f235314

Call-ID: 08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060

CSeq: 104 INVITE

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY, MESSAGE, SUBSCRIBE, INFO

Content-Type: application/sdp

Supported: replaces

User-Agent: X-Lite 4 release 4.0 stamp 58832

Content-Length: 371

v=0

o=- 12938412641879229 3 IN IP4 192.168.1.4

s=CounterPath X-Lite 4.0

c=IN IP4 192.168.1.4

t=0 0

a=ice-ufrag:4e8652

a=ice-pwd:ba7d4da3686f1e7c6c530f3c773ae3e7

m=audio 62964 RTP/AVP 0 101

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-15

a=sendrecv

a=candidate:1 1 UDP 659136 192.168.1.4 62964 typ host

a=candidate:1 2 UDP 659134 192.168.1.4 62965 typ host

Message Direction [Network]
From	192.168.1.4 [6000]
To	192.168.1.2 [Asterisk]
Dialog: [Dialog ID]
Call ID	08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060
Local Tag	73907587
Remote Tag	as6f235314
Dialog initiated?	Established
Dialog [Parameters]
Local Seq No	-
Remote Seq No	104 INVITE
Local URI	Sip:6000@192.168.1.4:23718
Remote URI	sip:6001@192.168.1.2
Remote Target	sip:6001@192.168.1.2:5060
Secure Flag	N
Route Set	192.168.1.2:5060
Transaction
Branch Parameters of Via	z9hG4bK4fc5ca1e
Cseq	104 INVITE

Session Parameters [SDP]
Session ID	12938412641879229	Session Version	3
Message From	192.168.1.4	Message To	192.168.1.2
Codecs	PCMU[0]	Target RTP To	192.168.1.4:62964
Start Time	0	End Time	0

19. ACK [Asterisk to Called]

ACK sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26 SIP/2.0

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK07cee6f2;rport

Max-Forwards: 70

From: "Balakrishnan" &~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as6f235314

To: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26&~~SPECIAL_REMOVE!#~~gt;;tag=73907587

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2:5060&~~SPECIAL_REMOVE!#~~gt;

Call-ID: 08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060

CSeq: 104 ACK

User-Agent: Asterisk PBX SVN-trunk-r300045

Content-Length: 0

Message Direction [Network]
From	192.168.1.2 [Asterisk]
To	192.168.1.4 [6000]
Dialog: [Dialog ID]
Call ID	08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060
Local Tag	as6f235314
Remote Tag	73907587
Dialog initiated?	Established
Dialog [Parameters]
Local Seq No	104 ACK
Remote Seq No	-
Local URI	sip:6001@192.168.1.2
Remote URI	sip:6000@192.168.1.4:23718
Remote Target	sip:6000@192.168.1.4:23718
Secure Flag	N
Route Set	192.168.1.2:5060
Transaction
Branch Parameters of Via	b31487650f177b26
Cseq	104 ACK

RTP Established between Called and Caller Directly

20. BYE [Called to Asterisk]

BYE sip:6001@192.168.1.2:5060 SIP/2.0

Via: SIP/2.0/UDP 192.168.1.4:23718;branch=z9hG4bK-d8754z-4b27e0a39c4799e3-1---d8754z-;rport

Max-Forwards: 70

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26&~~SPECIAL_REMOVE!#~~gt;

To: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as6f235314

From: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26&~~SPECIAL_REMOVE!#~~gt;;tag=73907587

Call-ID: 08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060

CSeq: 2 BYE

User-Agent: X-Lite 4 release 4.0 stamp 58832

Content-Length: 0

21. 200 OK [Asterisk to Called]

SIP/2.0 200 OK

Via: SIP/2.0/UDP 192.168.1.4:23718;branch=z9hG4bK-d8754z-4b27e0a39c4799e3-1---d8754z-;received=192.168.1.4;rport=23718

From: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.4:23718;rinstance=b31487650f177b26&~~SPECIAL_REMOVE!#~~gt;;tag=73907587

To: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as6f235314

Call-ID: 08d1e02e58e284044484e3bf49b72851@192.168.1.2:5060

CSeq: 2 BYE

Server: Asterisk PBX SVN-trunk-r300045

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH

Supported: replaces, timer

Content-Length: 0

22. Invite [Asterisk to Caller]

INVITE sip:6001@192.168.1.3:19048 SIP/2.0

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK220ac2f5;rport

Max-Forwards: 70

From: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as0ac5182d

To: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=ba82e016

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2:5060&~~SPECIAL_REMOVE!#~~gt;

Call-ID: Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.

CSeq: 103 INVITE

User-Agent: Asterisk PBX SVN-trunk-r300045

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH

Supported: replaces, timer

Content-Type: application/sdp

Content-Length: 271

v=0

o=root 1277759869 1277759871 IN IP4 192.168.1.2

s=Asterisk PBX SVN-trunk-r300045

c=IN IP4 192.168.1.2

t=0 0

m=audio 12832 RTP/AVP 0 101

a=rtpmap:0 PCMU/8000

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-16

a=silenceSupp:off - - - -

a=ptime:20

a=sendrecv

23. 200 OK [Caller to Asterisk]

SIP/2.0 200 OK

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK220ac2f5;rport=5060

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.3:19048&~~SPECIAL_REMOVE!#~~gt;

To: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=ba82e016

From: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as0ac5182d

Call-ID: Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.

CSeq: 103 INVITE

Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY, MESSAGE, SUBSCRIBE, INFO

Content-Type: application/sdp

Supported: replaces

User-Agent: X-Lite 4 release 4.0 stamp 58832

Content-Length: 371

v=0

o=- 12938412643424210 3 IN IP4 192.168.1.3

s=CounterPath X-Lite 4.0

c=IN IP4 192.168.1.3

t=0 0

a=ice-ufrag:692c3c

a=ice-pwd:4c8da4ea941b5b1164acc5b44e5918ce

m=audio 64356 RTP/AVP 0 101

a=rtpmap:101 telephone-event/8000

a=fmtp:101 0-15

a=sendrecv

a=candidate:1 1 UDP 659136 192.168.1.3 64356 typ host

a=candidate:1 2 UDP 659134 192.168.1.3 64357 typ host

24. ACK [Asterisk to Caller]

ACK sip:6001@192.168.1.3:19048 SIP/2.0

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK24165375;rport

Max-Forwards: 70

From: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as0ac5182d

To: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=ba82e016

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2:5060&~~SPECIAL_REMOVE!#~~gt;

Call-ID: Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.

CSeq: 103 ACK

User-Agent: Asterisk PBX SVN-trunk-r300045

Content-Length: 0

25. BYE [Asterisk to Caller]

BYE sip:6001@192.168.1.3:19048 SIP/2.0

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK0c066e51;rport

Max-Forwards: 70

From: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as0ac5182d

To: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=ba82e016

Call-ID: Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.

CSeq: 104 BYE

User-Agent: Asterisk PBX SVN-trunk-r300045

X-Asterisk-HangupCause: Normal Clearing

X-Asterisk-HangupCauseCode: 16

Content-Length: 0

26. 200 OK [Caller to Asterisk]

SIP/2.0 200 OK

Via: SIP/2.0/UDP 192.168.1.2:5060;branch=z9hG4bK0c066e51;rport=5060

Contact: &~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.3:19048&~~SPECIAL_REMOVE!#~~gt;

To: "Balakrishnan"&~~SPECIAL_REMOVE!#~~lt;sip:6001@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=ba82e016

From: &~~SPECIAL_REMOVE!#~~lt;sip:6000@192.168.1.2&~~SPECIAL_REMOVE!#~~gt;;tag=as0ac5182d

Call-ID: Mzk3OGYyMzA0MzYwZjJhZDJiNjBmMTJjYTNhMGJlNDA.

CSeq: 104 BYE

User-Agent: X-Lite 4 release 4.0 stamp 58832

Content-Length: 0