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?
Thanks for any help.
--
Iñaki Baz Castillo <[email protected]>
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