keith has submitted this change. ( https://gerrit.osmocom.org/c/osmo-msc/+/28509 )

Change subject: Change CC_CAUSE returned on unanswered MT Call ......................................................................

Change CC_CAUSE returned on unanswered MT Call

The timer "mgw X2" (RTP stream establishing timeout) is set by default to 30 seconds. When an MT call is ringing and remains unanswered, it is this timer that will expire, and the call is terminated.

Up to now this results in a CC_CAUSE of Resource Unavailable and if osmo-sip-connector is in use, the SIP agent will get 503 Service Unavailable. While "resource unavailable" may be technically correct, in that the MGW did not return an rtp stream in time, returning "No User Responding" (resulting in SIP 480) is probably a more accurate description of what actually happened, allowing the switch to inform the caller.

Change-Id: I4a9cfc388ec9ecb743d154a114a6db638eac4701 --- M src/libmsc/gsm_04_08_cc.c 1 file changed, 2 insertions(+), 0 deletions(-)

Approvals: laforge: Looks good to me, but someone else must approve neels: Looks good to me, but someone else must approve keith: Looks good to me, approved pespin: Looks good to me, but someone else must approve Jenkins Builder: Verified

diff --git a/src/libmsc/gsm_04_08_cc.c b/src/libmsc/gsm_04_08_cc.c index 8132de5..99174de 100644 --- a/src/libmsc/gsm_04_08_cc.c +++ b/src/libmsc/gsm_04_08_cc.c @@ -278,6 +278,8 @@ if (trans->cc.mncc_initiated) { mncc_release_ind(trans->net, trans, trans->callref, GSM48_CAUSE_LOC_PRN_S_LU, + (trans->cc.state == GSM_CSTATE_CALL_RECEIVED) ? + GSM48_CC_CAUSE_USER_NOTRESPOND : GSM48_CC_CAUSE_RESOURCE_UNAVAIL); }