How to change the default play on phone number used by Exchange UM?

A couple of months back my workplace decided to embark upon OCS federation and the enablement of public Live Meetings, a little late to the party I know – but better late than never! 🙂

When we originally planned our deployment (3 or so years ago) we decided to use internal SIP addresses only (i.e. firstname.lastname@company.local) so as a part of our move toward OCS federation we were forced to shift to public facing addresses (i.e. This of course resulted in a change to our existing SIP addresses and two migration pain points:

  1. Live Meeting scheduling data was now invalid and required updating (manual intervention seemed to be the best option here)
  2. Default Exchange UM addresses, stored within Outlook, were incorrect. I’ll go on to explain this in more detail

The scenario I am depicting here is one where you initiate a play on phone call via Outlook and you are presented with the dialogue below:

Given that my SIP address has changed to  this UM call would no longer route correctly. Therefore every time play on phone was initiated I needed to manually change the drop-down list to – which becomes very annoying over a prolonged period of time.

The play on phone number is initially set by OCS when you enable a user and specify their SIP URI, when SIP addresses are subsequently updated numbers are added and the old address left as-is. In addition the numbers are not re-prioritised – the default number will still be set to the previous address. To change this default setting I at first I started crawling the registry and discovered multiple references to my old SIP address – I realised pretty quickly that the scope for damage was high and chance of success low-to-medium! 🙂

I am ashamed to admit that the solution to my problem was far more simple, it was within the Outlook voicemail options (see below):

With this updated my default address for Exchange UM play on phone was now correct and I no longer needed to fiddle with the drop-drop. 🙂