The answer to this is actually pretty simple: adding Referred-By in outgoing SIP REFERs is simply not implemented in chan_pjsip's chan_pjsip_transfer() function.

As far as the syntax required for the Transfer() application, that's probably a case where that needs to be clarified in documentation. There are lots of places in PJSIP configuration where we require full SIP URIs rather than just IP addresses or bare URIs (user@domain).

On 08/25/2015 10:00 AM, Dan Cropp wrote:

I asked the question on asterisk–users but did not receive a response, so I am sending the question here.

I am running Asterisk 13.5.0.

A call comes in, Asterisk answers it. After some actions, the call needs to be Transferred (SIP REFER) to another number. The other switch is responsible for accepting the Transfer and tromboning the lines internally. It will also send a BYE so Asterisk no longer has the call.

The behavior works when I have the endpoint configured at chan_sip. It does not work when the endpoint is configured as PJSIP. I worked with the other switch vendor and he determined chan_sip includes the Referred-By header. PJSIP does not include the Referred-By header. The other switch requires the Referred-By header to be present.

I tried setting the channel’s SIPREFERREDBYHDR variable before the Transfer command and that still did not force the Referred-By header to be part of the REFER packet.

I tried the PJSIP_HEADER add and it still did not add the Referred-By header to the REFER packet.

Is there a PJSIP setting to force the Referred-By to be part of the REFER packet?

chan_sip (succeeds)

19:27:32.512123 IP (tos 0x0, ttl 64, id 11492, offset 0, flags [none], proto UDP (17), length 630)

    192.168.xxx.xxx.sip > 192.168.yyy.yyy.sip: SIP, length: 602

        REFER sip:[email protected]:5060 SIP/2.0

        Via: SIP/2.0/UDP 192.168.xxx.xxx:5060;branch=z9hG4bK58f4bd1d

        Max-Forwards: 70

        From: <sip:[email protected]>;tag=as44000cf4

        To: <sip:[email protected]>;tag=7Iy0JkwDC

        Contact: <sip:[email protected]:5060>

Call-ID: [email protected] <mailto:[email protected]>

        CSeq: 102 REFER

        User-Agent: Asterisk PBX 13.5.0

        Date: Thu, 20 Aug 2015 19:27:32 GMT

        Refer-To: <sip:[email protected]>

        Referred-By: <sip:[email protected]:5060>

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

        Supported: replaces, timer

        Content-Length: 0

Pjsip

18:46:58.386372 IP (tos 0x0, ttl 64, id 38690, offset 0, flags [DF], proto UDP (17), length 654)

    192.168.xxx.xxx.sip > 192.168.yyy.yyy.sip: SIP, length: 626

        REFER sip:[email protected]:5060 SIP/2.0

Via: SIP/2.0/UDP 192.168.xxx.xxx:5060;rport;branch=z9hG4bKPjec41c3b9-d734-482d-82c1-2a6f8d9452a3

From: <sip:[email protected]>;tag=3c10f423-e468-42ea-87a1-658ae106581c

        To: <sip:[email protected]>;tag=WITKDakt

        Contact: <sip:192.168.xxx.xxx:5060>

Call-ID: [email protected] <mailto:[email protected]>

        CSeq: 981 REFER

        Event: refer

        Expires: 600

        Supported: 100rel, timer, replaces, norefersub

        Accept: message/sipfrag;version=2.0

        Allow-Events: message-summary, presence, dialog, refer

        Refer-To: <sip:[email protected]>

        Max-Forwards: 70

        User-Agent: Asterisk PBX 13.5.0

        Content-Length:  0

One other slight oddity.

To get chan_sip to Transfer

[email protected] <mailto:[email protected]>

To get PJSIP to Transfer with the correct Refer-To header, I had to include the <> and sip:

<_sip:[email protected].__yyy_>

Have a great day!

Dan




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