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MGCP PSTN ringback

Hi

When I call to the PSTN using MGCP ringback tone

Which party generates the tone?

The DSP in the GW or the telco switch?

Thanks

2 REPLIES
Silver

Re: MGCP PSTN ringback

Excerpts from the book "Cisco IP Communications Express"

When an IP Phone hosted by Callmanager places an outbound call to the PSTN, the ringback tone heard by the caller is usually generated as an audio signal that's passed through end-to-end from the PSTN trunk (in-band tone). This means the audio path from the gateway to the IP Phone is opened and active before the call is connected.

Regards,

Anup

Green

Re: MGCP PSTN ringback

As a side note when you place an outbound call if using MGCP with PRI for example after you get the PROCEEDING from the PSTN you will get a MDCX sent from the CCM or CA to GW so audio is passed from GW to IP phone as previous poster stated.

The MDCX will be send after CCM has opened audio channel in IP phone (STM using 200 OK from CRCX, ORC ack).

If talking about an FXS|FXO we will expect the hd and oc message in MGCP from the GW indicating that everything at MGCP and voice port level is ok. So audio is passed through

HTH

//G

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