What is a SIP Polling ReInvite
A polling reINVITE is a periodic INVITE request sent by the Metaswitch call agent to a SIP endpoint whilst that endpoint is involved in an active call (session).
Polling reINVITEs are sent as follows:
For a registered SIP binding, the reINVITE is sent every 30 seconds, with the first one being sent between 0 and 30 seconds into the call.
For a configured SIP binding the behaviour is controlled by the 'Poll peer device' field on the configured SIP binding object (Call Agent -> Controlled Networks -> Configured Sip Bindings -> Configured SIP binding)
a) If the field is set to 'false', the behaviour is the same as for a registered SIP binding. That is, the reINVITE is sent every 30 seconds, with the first one being sent between 0 and 30 seconds in to the call.
b) If the field is set to 'true', the reINVITE will be sent every 15 minutes, with the first one being sent approximately 15 minutes in to the call. In this case the Metaswitch call agent will also be sending OPTIONS requests to the SIP device (the interval between these messages being controlled by the 'Polling interval' field on the configured SIP binding object). OPTIONS requests are also sent when the device is not in a call, so that the Metaswitch call agent can tell if the device is available