In order for your phone to recognize an outlook contact, the number must be entered using the e.164 format. E.164 number formatting is the internationally-standardized format for all phone numbers, and it includes all the relevant information to route calls globally. E.164 numbers can have a maximum of fifteen digits and are usually written as follows: [+][country code][subscriber number including area code].
For example, to convert a US phone number like 415 555 2671 to E.164 format, you need to add the ‘+’ prefix and the country code (which is 1) in front of the number so it will look like +14155552671.
To convert an existing contact, click on the number from the contact in outlook, and it will adjust itself. Once re-formatted, re-start outlook and your Polycom phone