Stop Outlook from reformatting telephone numbers

A telephone number gets reformatted when adding it to a contact in Outlook, e.g. "+31.." becomes "31".

This behaviour can be stopped as follows:

• Start, Search: "phone" and hit enter. If this doesn't work, then start the Telephony service:
• Start, Search: "services" and hit enter - Double click Telephony (TapiSvr)
• Startup type: automatic
• Click Start
• In the Phone and Modem screen, select a location or, if required, make a new location and use anything for the area code
• Click Edit..
• Country/region: Internation Freephone Service
• (Stop and) start Outlook

Note: it doesn't stop reformatting completely.

E.g. "+31-12345678" still gets reformatted to "+31 12345678", but at least the starting "+" sign remains untouched. And "+31612345678" gets reformatted to "+31612345678 "