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DTMF UC540/Metaswitch issue resolved

After three weeks of brutal agony, a solution....

Problem: outbound calls from UC540, all SPA525G2 phones through carrier using Metaswitch failed to pass DTMF to PSTN.

Metaswitch published two different config guidelines around the UC500.  The Doc ID 9465 (can't post link - need to be a metaswitch customer) says 711ulaw, rtp-nte - which is what TAC said.  But it didn't work.  Another doc, I don't have the number, said Metaswitch will only support out-of-band. 

Nothing in CCA allows for rtp-nte out-of-band but CME does support it (and maybe this is the solution to those having skype issues?)

Configuring Metaswitch for in-band was a total failure. Setting it to out-of-band and setting notify or info on the cisco side also were dead-ends.

This worked:

voice-class sip dtmf-relay force rtp-nte

dtmf-relay rtp-nte digit-drop

(if you don't know where this would go or how to apply it, just don't do it...)

I run the risk of CME trying to send digits both in and out of band but since the meta-switch is ignoring/unresponsive to the in-band messages, it seems to work ok.


Ambleside Logic

John Platts

The option to adjust DTMF settings for SIP trunks should really be added to the CCA SIP trunking window. In addition, the following options should be added to the CCA SIP trunking window:

  • The preferred codec for outbound SIP calls
  • The codecs allowed for inbound and outbound SIP calls
  • Enabling the P-Asserted-Identity header for outbound SIP calls
  • Enabling video for inbound and outbound SIP calls
  • Enabling and disabling moved-temporarily and refer for SIP calls

Reasons why these options should really be added to the CCA SIP trunking window include:

  • Some UC500 customers really need P-Asserted-Identity enabled for outbound SIP calls. We use a SIP gateway that requires the P-Asserted-Identity header. This feature already works properly with the UC500 7.0.2 software pack or later, but there is no CCA support for this feature yet.
  • Some of the SIP providers support G.711 A-law, G.722, and/or iLBC codec, in addition to G.711 mu-law and G.729. We use a SIP gateway that supports G.711 mu-law, G.711 A-law, and G.729. All of the Cisco IP phones support G.711 mu-law, G.711 A-law, and G.729. In addition, the G.722 codec is supported on most of the newer 7900 series phone models, and on all of the SPA500, SPA300, 8900, and 9900 series phone models. The iLBC codec is supported on the 7906, 7911, 7942, 7945, 7962, 7965, 7975, 8961, 9951, and 9971 phones.
  • Some users prefer to use the G.729 or iLBC codec as the preferred codec for outbound calls in order to reduce bandwidth usage, whereas some users prefer to use G.711 or G.722 in order to provide better audio quality. G.729 or G.711 will almost always be enabled to ensure that calls can be made to endpoints that do not support the G.722 or iLBC codecs.
  • The UC500 can make and receive video calls over SIP trunks on phones that are connected to PC's running Cisco Unified Video Advantage if video codecs are enabled on the outbound dial peer and the UC500 has the 7.1.0 software pack or later installed.
  • Support for making video calls to and from 9900 series phones in Cisco Unified CME is already planned.
  • Some SIP providers support the moved temporarily and/or REFER, but other SIP providers do not support these features. The moved temporarily and REFER features have to be disabled if the SIP provider does not support these features.
  • Some of these settings have to be set on the UC500 in order for the UC500 to be used with some SIP providers, and partners should not have to use CLI to set any setting that is essential to getting SIP calling working.
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