Missing SDP from Grandstream WP825


A call to the grandstream wp825 is dismissed > after 180 ringing there was no SDP from the grandstream, and the pbx than cancel the call.



180 do not generate sdp ?
183 generate sdp


Sure - but after the 180 ringing, an SDP should be sent from the grandstream, right?


No, 180 generate at caller side. GS will not open sdp.


The SDP will be generated when the call is answered (200OK) or, as Marcin indicated, if the UCM starts with a session progress (183) which is unlikely given that the call is destined for a device on the same network and presumably, the UCM knows if the device is registered.