This blog article outlines various policy options for internal phone calls.

Start in the TelephoneIntegration setup to determine the policy for internal phone calls. Within the Behaviour-tab, you have several options to do so.

In case of TAPI calls, internal calls are often represented by an extension number. 

For example, let us pretend that your office phone number was +43 (0)316 6880880 28. The number consists of [+CountryCode ](0) [LocalAreaCode][Number][Extension].
In this example, 28 is the extension number and two digits long.
Now, if you would like to define external calls, you need to set 3 as the minimum number length for external calls. In case you are using OCS or Lync, you can define your internal domain(s). For example, if your Lync SIP account is alist@mscrm-addons.com, you would set mscrm-addons.com as internal domain.
Please note: multiple domains must be separated with a semicolon (;).

The policy for internal incoming and outgoing calls can be set separately.
You can determine if the TelephoneIntegration balloon should pop up for incoming and/or outgoing calls or not.
Furthermore, you can determine that TelephoneIntegration should look up the internal number in CRM.
Regarding to this option, you can decide whether TelephoneIntegration should return all records with phone numbers that end with the specific extension number (in our example this would be the 28) or only those whose phone number exactly corresponds to this extension number.

If you prefer the latter case, you need to activate the Only exact matches-check-box (see Figure 1). Additionally, you can determine, if Internet Explorer windows should pop up for incoming and/or outgoing internal calls.

That’s it! We appreciate your feedback! Please share your thoughts by sending an email to support@mscrm-addons.com.