CUCM:Line CSS & Device CSS

Before going ahead I hope you know the terms CSS and Partitions very well.If not you take a look at here.

Device CSS is applied to the IP phone added in the CUCM.Line CSS is applied to the Line / directory number.

If both CSS applied together then line CSS get higher priority and device CSS get second priority.

Cisco recommends to apply route pattern to the device and apply block pattern to the line CSS.

Here we take an example of making Local,Long distance,International and emergency calls.
We have PHONE_A with line number 1001. PHONE_A is allowed to call Local Numbers  and Emergency calls only.

For that we need to create two CSS. One in which contains all patterns  and in second we keep only blocked patterns.

CSS_Allow_ALL contains following partitions.

PT_Local
PT_Internation
PT_Longdistance
PT_Emergency

For the blocking we keep blocked numbers : Long distance partition and International partition in
CSS_Block.

CSS_Block contains following partitions.

PT_Internation
PT_Longdistance

So, Here we applied CSS_Allow_ALL to PHONE_A's device CSS and CSS_Block to PHONE_A's line CSS.With that PHONE_A is allowed to call only Local Numbers and Emergency calls only.