Draytek Vigor2110 Series User Manual page 69

Loop through
Backup Phone Number
Vigor2110 Series User's Guide
the same SIP server, sometimes, the VoIP phone call
connection may not succeed. By using the specified dial out
account, the successful connection can be assured.
The selection should be as the following:
When the VoIP phone is obstructs or the Internet breaks down
for some reasons, the backup phone will be dialed out to replace
the VoIP phone number. At this time, the phone call will be
changed from VoIP phone into PSTN call according to the loop
through direction chosen. Note that, during the phone switch,
the blare of phone will appear for a short time. And when the
VoIP phone is switched into the PSTN phone, the telecom co.
might charge you for the connection fee. Please type in backup
phone number (PSTN) for this VoIP phone setting.
59