DTMF fails to work through the ISDN Gateway from an IP endpoint
Updated:Jul 07, 2011
Why does DTMF fail to work through the Cisco TelePresence ISDN GW from an IP endpoint?
The Cisco TelePresence ISDN Gateway does not transcode out-of-band DTMF to in-band DTMF for video calls.
In Cisco TelePresence ISDN Gateway versions earlier than release 1.4 the gateway advertised out-of-band DTMF for video calls. Most IP endpoints chose to use out-of-band DTMF in preference to in-band DTMF and therefore DTMF would work with the gateway auto-attendant but would not be detected by endpoints on the ISDN side of the network.
In release 1.4 and later, the Cisco TelePresence ISDN Gateway no longer advertises out-of-band DTMF for video calls. IP endpoints should therefore use in-band DTMF as audio tones, which the gateway will forward to the ISDN endpoint. However, note that some IP endpoints may still try to send out-of-band DTMF (which will not be forwarded over ISDN).
This article applies to the following products:
Cisco TelePresence ISDN GW 3200 and 3241 / MSE 8310 and 8321 ISDN blades