I am having problems getting 7975's to send DTMF across a SIP trunk. Other phones such as my 8865 can complete this with out issue. The SIP trunk in question is linked to another vendor PBX.
I have attempted to use a MTP, but no change in symptoms occurred.
I have tried with the trunk DTMF Signaling Method set at no preference, RFC2833, and OOB + RFC2833. No option provided a resolution.
7975 SIP 9-4-2SR2-2S
Any suggestions is greatly appreciated.
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