What is the purpose of the directory number calling search space?

[cisco.smj]

If the device CSS is used when making calls and the specific forwarding CSS is used when forwarding calls. What is the directory number CSS used for?

[Les Pruden · Accepted solution]

Hi -

There is a lot on this topic in this forum - you can do a search.  Also, great information on this in the SRND - look at the dial plan - Calling Privileges in Unified CM section

https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/srnd/collab11/collab11/dialplan.html?bookSearch=true 

Regards,

Les

[cisco.smj]

I did a search, but I assume the terms I was using were not coinciding with the terms that would have got me the answer.

From my short amount of testing after reading the SRND.

When placing a call the device-CSS and the line-CSS are both used. This allows you to expand your total calling search space.

Thanks for the quick response.

[BradEast1]

You could potentially have multiple DN's assigned to a single phone, each requiring a unique CSS.