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dexter gerrit-no-reply at lists.osmocom.orgdexter has uploaded this change for review. ( https://gerrit.osmocom.org/11169 Change subject: running: Add note about DTMF support ...................................................................... running: Add note about DTMF support osmo-sip-connector does not yet support full DTMF support. The current implementation only supports DTMF tones to be send from MNCC to SIP, but not in the opposite direction. Change-Id: I578e50b0a42d88b05cf6da80443b71494b5eb26f Related: OS#2777 --- M OsmoSIPConnector/chapters/running.adoc 1 file changed, 26 insertions(+), 0 deletions(-) git pull ssh://gerrit.osmocom.org:29418/osmo-gsm-manuals refs/changes/69/11169/1 diff --git a/OsmoSIPConnector/chapters/running.adoc b/OsmoSIPConnector/chapters/running.adoc index 5e0d583..85ccddc 100644 --- a/OsmoSIPConnector/chapters/running.adoc +++ b/OsmoSIPConnector/chapters/running.adoc @@ -56,3 +56,29 @@ socket-path /tmp/msc2_mncc ---- +=== DTMF signaling + +In VoIP based telephony networks DTMF (Dual-tone multi-frequency signaling) can +be signaled through multiple methods. Common methods are in-band, RFC2833 and +sip-info messages. + +Osmo-sip-connector is using sip-info messages to signal DTMF tones. When a DTMF +tone is signaled at the MNCC socket interface, osmo-sip-connector will generate +a matching sip-info message to forward the DTMF signal to the PBX. Depending on +the PBX software reconfiguring the DTMF signaling method to sip-info may be +necessary. + +While sending DTMF tones through the MNCC interface to a SIP leg, the current +implementation of osmo-sip-connector does not support sending DTMF tones in the +opposite direction. Any attempts to send DTMF tones to an MNCC leg will be +confirmed with a status 405 "Method not allowed". + +The reason for this limitation is that in mobile networks, depending on the +signaling direction, the signaling of DTMF tones is implemented differently. +A mobile originated DTMF tone is signaled through out of band messages, +which arrive at osmo-sip-connector on as MNCC DTMF START/STOP messages. Those +messages can be directly translated to sip-info messages. However, in the +other direction (mobile terminated), an in-band signaling method is used. This +means that osmo-sip-connector would have to translate an incoming DTMF sip-info +message into an audio sample that then would have to be injected into the +voice stream. Currently this scheme is not implemented in osmo-sip-connector. \ No newline at end of file -- To view, visit https://gerrit.osmocom.org/11169 To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: osmo-gsm-manuals Gerrit-Branch: master Gerrit-MessageType: newchange Gerrit-Change-Id: I578e50b0a42d88b05cf6da80443b71494b5eb26f Gerrit-Change-Number: 11169 Gerrit-PatchSet: 1 Gerrit-Owner: dexter <pmaier at sysmocom.de> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.osmocom.org/pipermail/gerrit-log/attachments/20181001/8936160d/attachment.htm>