Depending on how you intend to use a phone number, you will want to configure your numbers for inbound calls, outbound dialing, SMS, or a combination.
For example, you may have numbers that you only want to be used for inbound call tracking. Alternatively, numbers that you are using for outbound dialing should also be configured for inbound calls in order to facilitate call backs.
The following articles walk through configuring phone numbers and provide details on the available settings: