signal vs. signal-update...

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Jul 21st, 2009
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I occasionally get DTMF tones from my carrier in a signal-update vs. a signal. When my AS5400 receives these messages I send back a 400 Bad Request. I have tried to change my dial-peer to dtmf-relay h245 signal but it didn't help. Anyone know how I should handle these occasional SIP messages? TIA.

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Nicholas Matthews Tue, 07/21/2009 - 09:34
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I'm confused because:

h245-signal and signal-update are H323 messages.

400 Bad Request is a SIP message.

Every signal should be followed up by a signal-update to mark the end of the digit, but that is for an H323 call.

Can you explain the call flow more?


snickered Tue, 07/21/2009 - 10:12
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Exactly. I'm getting signal-update in a SIP INFO message from my carrier. I have a simple setup. Just doing SIP->TDM. Calls that don't have this signal-update message work fine with 'dtmf-relay cisco-rtp'. I'm wondering if there's a way to handle these types of messages or if I need to tell my carrier to get their act together. ;)

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

Via: SIP/2.0/UDP yyy.yyy.yyy.yyy:5060;branch=z9hG4bK0dBea481531b543eab1

From: "Cell Phone TX" [email protected];isup-oli=62;pstn-params=808482808882>;tag=gK0d5bb22f

To: [email protected]>;tag=213985C4-414

Call-ID: [email protected]

CSeq: 30593 INFO

Max-Forwards: 70

Supported: 100rel

Content-Length: 33

Content-Type: application/dtmf-relay

Signal-Update= 8

Duration= 325

Nicholas Matthews Tue, 07/21/2009 - 10:38
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There isn't going to be anything on the gateway to support this. Just looked up the spec that we use, and we're looking for signal= .

If you can, have them update that field and you'll be alright. Otherwise ask for RFC 2833 as it is more of a SIP standard for DTMF than it is for anything else.


snickered Tue, 07/21/2009 - 11:05
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My carrier told me that I need to allow for signal-update or just discard it. Is there a way I can discard these?

Nicholas Matthews Tue, 07/21/2009 - 11:20
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The only option that may get you this is a new feature in 12.4(22)YB:

voice service voip


pass-thru content unsupp

I have my doubts about this, so you will probably need to push back on the provider.

Considering that an INFO message requires a response, ignoring it isn't an option.



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