Provides access to information about the telephony services on the device. Applications can use the methods in this class to determine telephony services and states, as well as to access some types of subscriber information. Applications can also register a listener to receive notification of telephony state changes.

You do not instantiate this class directly; instead, you retrieve a reference to an instance through Android.Content.Context.GetSystemService(string).

Note that access to some telephony information is permission-protected. Your application cannot access the protected information unless it has the appropriate permissions declared in its manifest file. Where permissions apply, they are noted in the the methods through which you access the protected information.

[Android Documentation]