What if some incoming calls work, and some fail?

In some installations, calls from certain numbers work reliably, while calls from other numbers never get through. There are two common reasons for this.

In a typical customer premises installation of R2, the number of dialled digits will be same for every call. If you specify the expected number of dialled digits to be greater than this number, you may get trouble. When calls from some locations arrive, the dialled number may be correctly terminated by an "end of dialed number" signal. Calls arriving from other places may never send this signal, and the call setup process may freeze until a timeout causes error recovery. The answer is to set the number of expected digits to the number actually expected. This makes call setup just a little faster too, as it is no longer necessary to exchange the "end of dialed number" signal.

The variants of MFC/R2 differ in the way they deal with the caller ID, or ANI, not being available. Some just present a zero length caller number. Some send a special code, to indicate the caller number is not available. It is possible that not every version of these codes is currently implemented in the software. You might, for example, find that incoming international calls fail, because a special code is used. If this happens turn on the logging, and monitor what happens differently with the calls which go wrong. Report it to the author, and it will be fixed.