Default Call Routing

In an IP Office Server Edition deployment with no other changes than the addition of SIP trunks to the primary server:

• The default short code/ARS configuration on the primary server routes all external calls to any trunk/channel in outgoing line group 0.

• If a secondary server is present, its default short code/ARS configuration route all external calls to outgoing line group 99999 (to the primary).

• For any expansion server's present, their default short code/ARS configuration routes all external calls to outgoing line group 99999 (to the primary) if available, else to outgoing line group 99998 (to the secondary).

The above provides only minimal resilience. Expansion systems unable to see the primary but able to see the secondary can still make external calls if the secondary can still access the primary. In the case above, the simplest method of adding some further resilience would be to also add SIP trunks to the secondary server. The secondary server's ARS would be reconfigured to use the outgoing line group of its own SIP trunks. Expansion systems unable to see the primary can then still make external calls using the secondary's SIP trunks.

Obviously, further resilience can be achieved by providing each location with its own trunks. This also simplifies the configuration of emergency call routing.

Using ARS Short Codes

By default, the short codes in an ARS form are used in the order entered in order to seize an available external trunk. Adding an additional short code however does not allow any further control, that route is automatically and immediately used if the preceding short code route is not available.

Using ARS Fallback

ARS forms can include an alternate route which redirects calls to another ARS form. See ARS Alternate Route Overflow.

Using ARS Out of Service

The out of service features of ARS allows calls to be redirected when it is known in advance that the trunks used by that ARS will not be available, for example for maintenance. See ARS Out of Service Routing

Using Breakout

The Breakout action is potentially useful during failover scenarios. It allows a telephone user to make a call as if dialing the digits on another system on the network and thus have their dialing routed by that system. The action can be assigned to short codes and to programmable buttons.