[SIPForum-discussion] SIP to PSTN

[HM Kias]

Hi Surya,

In generic terms, the gateway will map SIP messages to PSTN signaling
protocol such as ISDN or ISUP and the rtp session is converted by the
gateway to PCM.

The ISUP address complete message (ACM) is sent back by the PSTN to
indicate the trunk has been seized,  the gateway maps the ACM to the SDP
(183 session progess) indicating the RTP port that the gateway will bridge
the PSTN for the audio. Upon receiving the 183, the UAC starts receiving
the RTP packets from the gateway and presents the audio to the caller.

Regards,

Kias Hanifa

Fonicom



On Tue, Jan 15, 2013 at 5:07 PM, Suryakanta Behera <skbehera321 at gmail.com>wrote:

> Hi,
>
> I have a question. Can Anyone help
>
> "In between two user agent a C5 switch is present and one is sip user
> another is isup user , So who is responsible to convert SIP message to ISUP
> message in C5 switch. Actually what C5 are doing there & What are the
> functionality/Element contain C5 switch in particular situation".
>
> Another Question
> "In SIP to PSTN Call Flow In-between GW are there, Someone tell me after
> sending ACM message "from SSP to GW" then GW what  it will send 180/183, if
> it is sending 183-Res to SIP then Two-way RTP will flowing in between SIP
> to GW  and one-way media will flowing SSP to GW"
>
> Is it Correct ! If Correct, how two-way RTP will flowing in between SIP to
> GW  and one-way media will flowing SSP to GW.
>
>
>
> Please, describe briefly about this....
>
> Thanks & Regards
> Surya
>
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-- 
HM Kias
91-9443467600
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