On Mon, Jun 10, 2013 at 12:36 PM, Matthew Meek <mmeek@contractworld.jobs>wrote:
I am attempting to setup FS as an B2BUA SBC between a telco platform and a telco SIP trunk. Everything is fine except for one call-flow scenario: ** **
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We need to sometimes “reject” calls by sending reason code 17, which is quite easy by sending a SIP 486. The issue is that the far-end first receives early media and then the reason code 17, and the far-end switch is bonding the B-leg media for 55 seconds instead of moving on in the dial-plan. When comparing this to our PRI build-out, the difference is that in the PRI-buildout, no early-media is sent. In the SIP world, we are sending a 183 with SDP to setup the early media… ****
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If I don’t send early media, the telco will inject their own early media path… so I need a work-around.****
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The telco is asking that we send specifically a 183 WITHOUT SDP, which I am having trouble figuring out how to do. I know how to send the 180 WITHOUT SDP, a 183 WITH SDP, but I cannot find the solution to sending 183 WITHOUT SDP…****
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I know it is unusual to send 183 without SDP, but it is still RFC compliant…
From a quick glance at the FreeSWITCH code, it does not seem possible unless mod_sofia.c is modified to use nua_respond() SIP_183_SESSION_PROGRESS without specifying an SDP. Relatively small change probably, but still some coding is required.
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