I was recently at a client configuring Lync Dial-In Conferencing. All functionality worked within the Lync environment as well as between the internal Cisco phones.
When testing external PSTN access to the Lync Dial-In Conferencing bridge, I noticed that the call would connect with two-way audio but DTMF signaling was not being accepted. Below is a breakdown of the environment.
When testing external PSTN access to the Lync Dial-In Conferencing bridge, I noticed that the call would connect with two-way audio but DTMF signaling was not being accepted. Below is a breakdown of the environment.
My first thought was to add the “dtmf-relay rtp-nte” command to the voip dial peer on the voice router. When we took a look at the voip dial peer, we noticed that “dtmf-relay rtp-nte” had already been added. After further research and investigation, we determined that the H.323 gateway required its own DTMF relay command to pass DTMF tones out-of-band. We replaced the dtmf-relay command with “dtmf-relay h245-alphanumeric” and DTMF tones were accepted!
VOIP Dial Peer Before
| dial-peer voice 100 voip preference 2 destination-pattern 555555…. progress_ind setup enable 3 voice-class codec 1 voice-class h323 1 session target ipv4:X.X.X.X incoming called-number . dtmf-relay rtp-nte fax rate disable no vad ! |
VOIP Dial Peer After
| dial-peer voice 100 voip preference 2 destination-pattern 555555…. progress_ind setup enable 3 voice-class codec 1 voice-class h323 1 session target ipv4:X.X.X.X incoming called-number . dtmf-relay h245-alphanumeric fax rate disable no vad ! |
Further information regarding H.323 and DTMF frequency can be found below:
