<p>I expect that the contact should be like:</p>

<p>Contact: sip:xxxxxxxxxxxx@10.x.x.x:5060;alias=10.x.x.x~60911~2;+g.3gpp.icsi-ref="urn%3Aurn-7%3A3gpp-service.ims.icsi.mmtel";video;+sip.instance="urn:gsma:imei:xxxxxxxx-366xxx-0"</p>

<p>Starting with +g.3gpp.icsi-ref, it should be header parameter, not uri -- the uri is enclosed in between < >.</p>

<p>It might be that a node in the path is building the wrong Contact format.</p>

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