IP Office, back in the day, used to use TAPI to allow users to dial from Outlook Contacts. Now that Microsoft has entered the voice telephony, they have enhanced capabilities in their products.
With IP office Release 9, Avaya allowed the One-X portal desktop clients to enable the Smart Tag feature set. So, to have the ability that a user can click on a number in Outlook, Word or Excel, you first need to enable the Smart Tag options in Microsoft
Microsoft Outlook 2007:
1. In the Tools menu, select Options.