Subject: [SIP] Mapping of ISDN bearer and tele services

From: Lueken Joachim <[email-masked]>
Date: Tue, 13 Mar 2001 12:05:14 +0100

Hi all,

I am investigating the interworking between ISUP and SIP or SIP-T, respectively.

Looking into the drafts "Call Flow Examples" and the "ISUP to SIP mapping", I only found that USI "speech" is mapped to PT "0" PCMU. Furthermore, there is the special draft for T.38 dealing with Facsimlie G2/3 calls.

I wonder,

1) How are the remaining ISDN bearer and tele services (e.g. 64 kbps unrestricted, Fax G4, Videotelephony, ...) mapped to SDP?

2) Why is PT PCMU always mapped to "speech"? If a fax application would use G.711, then this mapping may result in call rejection at the destination fax terminal. I can also imagine problems in PSTN networks regarding echo control devices. In my opinion mapping PT PCMU or PCMA, respectively, to "3.1 kHz audio" is more appropriate.

----------------------------------------
Mit freundlichen Gruessen / kind regards
Joachim Lueken
SIEMENS
eMail: [email-masked]
----------------------------------------

_______________________________________________
This list is for continuing development of the SIP protocol.
The sip-implementor's list is the place to discuss implementation,
and to receive advice on understanding existing sip.
To subscribe to it, send mail to 
[email-masked] with "subscribe" in the body.