UM Telephone Numbers not replicating to all users

Good Morning/Evening all,

I currently have MS Lync 2010 4.0.7577 installed, everything is working perfectly for most people.

Certain people will use the Lync search feature to find a contact, when that contact is located they attempt to use the telephone function but it dosent work, the telephone number is now shown in their information.

But for example, when that end users colleague searches for that same person, they are able to find view and telephone that same person.

We currently use a Cisco CM server, I'm not sure where to start with this, i have done AD syncs on the cisco server and this still hasnt resolve the issue.

Any input would be greatly appreciated.

Thanks,

Hassan.