This article relates to the Cisco TelePresence ISDN GW 3241 and Cisco TelePresence ISDN GW MSE 8321 products.
Q. Why does DTMF fail to work through the Codian ISDN GW from an IP endpoint?
A. The Codian ISDN Gateway does not transcode out-of-band DTMF to in-band DTMF for video calls.
ISDN Gateway versions prior to the 1.4 release advertised out-of-band DTMF for video calls; with this software version most IP endpoints chose to use out-of-band DTMF in preference to in-band DTMF and therefore DTMF would work with the ISDN Gateway's auto-attendant but would not be detected by endpoints on the ISDN side of the network.
Upgrading to 1.4 or above will stop the ISDN Gateway advertising out-of-band DTMF for video calls; IP endpoints will have to use in-band DTMF, which the ISDN GW will forward to the ISDN endpoint.