Enterprise call notification is sometimes positioned relative to the PBX feature called simultaneous ring. Simultaneous ring refers to  incoming calls to the office being bridged to multiple phone numbers where the call is handed off to the first one that answers. If none answers, the call is passed to the voicemail engine for processing. Simultaneous ring is not considered a mobile UC feature since any phone number can be programmed as a target, not necessarily a mobile phone.

Some PBXs allow users of simultaneous ring to program the ringing circuits remotely.