Clamr!

Integration of Google Voice and Microsoft Outlook enables you to call, schedule auto-calls, text, conference call, broadcast text, play voicemails and transfer files in Microsoft Outlook. Free trial.

SKAIFO

SKAIFO is an Outlook Add-In that integrates Skype functionality with Microsoft Outlook. It has full-fledged User Interface inside Outlook so there is no need to switch back and force between Outlook and Skype for your free calling needs.

The BIG Number

This utility was designed to automatically update phone numbers held in Microsoft Outlook Contacts. It is compatible with all versions of Outlook up to & including Outlook 2007. The BIG Number includes a range of options to set the format of phone numbers to suit a variety of national and international conventions. It has formatting features that can tidy up numbers so that, for instance, you can choose whether all area codes should have brackets around them or add international dialling prefixes to all UK numbers. This can aid the process of synchronising the Outlook contact database with personal organisers and mobile phones. The latest version includes a custom replacement feature, handy if you become affected by a new area code change or have used a number format that Outlook doesn't interpret properly. Another recent addition is an option to remove all spaces from the numbers as some mobile devices can't handle them.