Problem With Cisco Phones

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Asterisk Users 7 Comments

Possibly slightly off topic, has anyone ever had Cisco 79xx Series phones come up with “cannot complete conference” errors when trying to conference two calls together?

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7 thoughts on - Problem With Cisco Phones

  • I’m willing to bet you are forcing the use of G729. 7940 and 7960 phones can only do a single G729 channel, and if you require G729 for the second leg of a conference, it will fail.

  • We were using G722 – I thought similarly and tried a call with alaw. Same problem occurred, any other ideas?

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  • Next step is packet capture to see if there is a clue as to the cause of the failure in the SIP signalling.

  • Right, I see the following when running SIP Debug. Looks to me like the phones are expecting the server to do the conference mixing, which I guess it would do in CallManager?

    <--- SIP read from TCP:xxx.xxx.xxx.xxx:50604 --->
    REFER sip:xxx.xxx.xxx.xxx SIP/2.0
    Via: SIP/2.0/TCP xxx.xxx.xxx.xxx:50604;branch=z9hG4bK48c7492c From: “4005” ;tag 3a07fceb4b00eff1377deb-da93e2ee To:
    Call-ID: OutOfDialog–001e-67a906f5-5333c2b8@xxx.xxx.xxx.xxx Max-Forwards: 70
    Date: Tue, 20 Jan 2015 17:10:19 GMT
    CSeq: 101 REFER
    User-Agent: Cisco-CP7945G/9.4.2
    Contact:
    Referred-By: “4005”
    Refer-To: cid:9a2a9191@xxx.xxx.xxx.xxx Content-Length: 963
    Content-Type: application/x-cisco-remotecc-request+xml Content-Disposition: session;handling=required Content-Id: <9a2a9191@xxx.xxx.xxx.xxx>


    Conference 203a07fc-eb4b001c-1bf7ad61-614d38c1@xxx.xxx.xxx.xxx 203a07fceb4b00ed3e4e2321-d9cb1581 as4a087ee2 0 0 203a07fc-eb4b001d-14750420-d3d10a57@xxx.xxx.xxx.xxx 203a07fceb4b00ee46f74fd6-4ed3acbd as18747c6d false explicit 0 0

    <------------->
    — (16 headers 3 lines) –

  • I’ve done some more playing about and what I’ve noticed is that even when using TCP SIP on the 8.x Firmware conferencing doesn’t work – making it use UDP fixes this.

    So has anyone managed to get the 9.x firmware working with UDP? Possibly worth a try to see if this resolves the issue?

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