User guide

Chapter 5: Phone Book Configuration
Multi-Tech Systems, Inc. MVPGSM 83
Internal Survivability Example: You have an MVPGSM with Channel 1 using SIP extension 301 and Channel 2
using SIP extension 302. A GSM call is received on Channel 1 and is intended for a remote office (809)
represented by the black arrows. Unfortunately, the survivability destination on the Internet is not
responding, so Local Survivability mode is processed, represented by the red arrows. With the survivability
link monitor reporting no connectivity, Internal Survivability routes the call to channel 2 if the VOIP as this is
the internal survivability route. There needs to be an inbound phone book entry for the survivability
number. If the inbound entry (Inbound Phone Book entry ‘302’ below) has a phone number in its Add Prefix
field that number will automatically be called. If not (as shown below), the caller will hear dial tone from the
GSM network and it can dial the desired destination.