Presence is at the core of the pillars of Unified Communications and it is important to understand how vendors are applying this important feature to their voice applications. Let’s look at Cisco Systems, who is now anchoring all of its voice product lines on version 7.
With Unified Communications Manager (CUCM) 7.x, you can enable presence in two ways. One way is to create BLF (busy lamp fields) and the other way is to add presence information into call lists. The presence that CUCM natively supports is on-hook or idle, off-hook or busy, and unknown status (most refer to this as “basic presence information”). For some companies, it would be enough to know that if someone I am trying to call is already on the phone, rather than waste the time to call, the call could be diverted until the line on the phone is free.
Additionally, this presence information can be shared with other Unified Communication Manager clusters by using SIP trunks and adjusting the SIP profile to send and receive presence information.
Now in order to use BLF’s to exchange presence information, you as the PBX administrator would have to:
- Create Subscribe calling search space
- Create a phone template, whereby assigning one of the available line button slots as a speed dial BLF.
- Assign the subscribe calling search space to the phone or end user needing the presence information and configure the speed dial of the extension that presence will be pulled from.
Note: The subscribe CSS is like a key set that contains an order list of partitions or locks that represent the numbers or extensions in which a presence request can be routed to. Additionally, it should be noted that 7905, 7906, 7911 and 7912 phones do not support presence BLF SD. If you desire to have this feature you must upgrade your phone type first.
In the next post on presence, we will look at presence call and directory lists and detail why presence policies are created for the cluster in order display presence in those listings.
Author: Joe Parlas