Partitions and CSS: Central Dial Plan and Emergency Call Routing

Partitions and CSSs are not just for calling restrictions…they are FUNDAMENTAL to being able to properly implement central dial plans and emergency call routing! In this Nugget, Jeremy explores the implementation and caveats of this concept.


*****Key Point: When a CSS on the LINE and DEVICE are combined, the LINE CSS is ‘searched’ upon first… then onto the DEVICE CSS***

Work example: LINE defines calling privileges (permit/block) and the DEVICE lets everything through as a kind of catch all.


This is where is gets pretty scary and pretty cool at the same time!

2 sites connected via the PSTN and WAN

2 PSTN dial plans are created… at each site. Same digits and same cluster.

All calls by default sent to the PSTN via a route pattern.

Patters are duplicated, but housed into different partitions with associated CSSs **KEY POINT**

So each site will have its own CSS which has it’s own route pattern to get to the PSTN with an associated gateway.

Emergency Call Routing works exacts the same way, so duplicate patterns are created and housed into geographical partitions.