How to suppress telephony errors on the client?

How can error messages coming from the telephony layer be suppressed on the XPhone Client?

Create a new key in the Windows registry:

HKEY_CURRENT_USER\Software\C4B\XPhone40\Phone

Name: ReportError

Type: DWORD

Value:

Default=1: Prio 1 Display errors

0: show no errors

2: show Prio 1 and Prio 2 errors

3: show all errors