Here's how to set up the SIP Options setting in SIP Peering Module. If you would like Polling enabled please check the tickbox and select save.
SIP OPTIONS polling enabled
2talk poll the primary trunk IP every minute.
If no response to the SIP OPTIONS is detected 3 additional OPTIONS checks are made within the next minute to rule out a dropped packet.
If there are no further responses the trunk fails over to the secondary IP (if configured) if not then it call forward unreachable logic is followed.
When failed over all calls on the trunk are routed to the failover IP.
In the background 2talk continue to poll the primary IP and once it has responded again/recovered will start routing calls to the primary IP again.
SIP OPTIONS polling disabled
If SIP OPTIONS polling is not enabled calls are only failed over on SIP timeout, which is 30 seconds.
This timeout applies for every call which can result in a negative experience for the inbound caller, waiting up to 30 seconds before the call starts to connect.
As a result 2talk recommend adding SIP OPTIONS but only if the customer PBX correctly supports responding to OPTIONs otherwise 2talk will failover the trunk immediately as soon as the feature is enabled which can cause issues.
The response to OPTIONS can be any response, all that is needed is some sort of response. For example the response can be an 200 OK or a 404 Not Found.
Outbound calls routing is determined by the end device. If an exception route has been configured 2talk will trust outbound calls from either of the IP's configured.