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Diffstat (limited to 'common/chapters/mncc.adoc')
| -rw-r--r-- | common/chapters/mncc.adoc | 26 |
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diff --git a/common/chapters/mncc.adoc b/common/chapters/mncc.adoc index 8825be3..3adbf7f 100644 --- a/common/chapters/mncc.adoc +++ b/common/chapters/mncc.adoc @@ -60,6 +60,32 @@ MNCC interface compatible with the Osmocom MNCC socket is `lcr`, the Linux Call Router. More widespread integration of external call routing is available via the OsmoSIPConnector. + +=== DTMF considerations + +In mobile networks, the signaling of DTMF tones is implemented differently, +depending on the signaling direction. A mobile originated DTMF tone is +signaled using START/STOP DTMF messages which are hauled through various +protocols upwards into the core network. + +Contrary to that, a mobile terminated DTMF tone is not transfered as an out of +band message. Instead, in-band signaling is used, which means a tone is injected +early inside a PBX or MGW. + +When using {program-name} with its built in MNCC functionality a mobile +originated DTMF message will not be translated into an in-band tone. Therefore, +sending DTMF will not work when internal MNCC is used. + +For external MNCC, the network integrator must make sure that the back-end +components are configured properly in order to handle the two different +signaling schemes depending on the signaling direction. + +NOTE: osmo-sip-connector will translate MNCC DTMF signaling into sip-info +messages. DTMF signaling in the opposite direction is not possible. +osmo-sip-connector will reject sip-info messages that attempt to signal +a DTMF tone. + + === MNCC protocol description The protocol follows the primitives specified in 3GPP TS 04.07 Chapter 7.1. |