El Viernes, 26 de Febrero de 2010, Iñaki Baz Castillo escribió: > Hi, I've some interoperability problems with a PBX sending DTMF events as > follows: > > RFC 2833 RTP Event > Event ID: DTMF Eight 8 (8) > 0... .... = End of Event: False > .0.. .... = Reserved: False > ..00 0000 = Volume: 0 > Event Duration: 0 > > > This DTMF is not recognized by my softswitch. But the following DTMF from a > different PBX is correctly detected: > > RFC 2833 RTP Event > Event ID: DTMF Eight 8 (8) > 0... .... = End of Event: False > .0.. .... = Reserved: False > ..00 1010 = Volume: 10 > Event Duration: 0 > > > The only difference is the "Volume" (0 in the first case, 10 in the second > case). However according to RFC 2833: > > volume: For DTMF digits and other events representable as tones, > this field describes the power level of the tone, expressed > in dBm0 after dropping the sign. Power levels range from 0 to > -63 dBm0. The range of valid DTMF is from 0 to -36 dBm0 (must > accept); lower than -55 dBm0 must be rejected (TR-TSY-000181, > ITU-T Q.24A). Thus, larger values denote lower volume. This > value is defined only for DTMF digits. For other events, it > is set to zero by the sender and is ignored by the receiver. > > So "Volume: 10" makes no sense for me, as it should be from 0 to -36, > right? Also, "Volume: 0" is the biggest value so there is no reason my > softswitch to ignore such DTMF due to its "Volume" value, am I right?
Ok, I understand that "Volume: 10" means -10 dBm0. From other device I can send DTMF with: Volume: 0 Event duration: 160 and it's correctly detected by the softswitch. Not sure if the Even Duration is important or not. But it's really strange that the following cases work: - Volume: 10, Event Duration: 0 - Volume: 0, Event Duration: 160 and the following case doesn't work: - Volume: 0, Event Duration: 0 Any explanation? how important is to set the Event Duration? Using my softphone I cannot set it to 0 value (minimun value allowed by the softphone is 40). Must it be greater than 40? Thanks. -- Iñaki Baz Castillo <[email protected]> _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
