ADTRAN Express 4100 - Manual (Page 64)

Chapter 3. Terminal Menu Operation and Structure
3-14 Express 4100/4110 User Manual 61200176L2-1
POTS/Speech Calltype Routing
Write security: 2; Read security: 5
This allows the Express 4110 to treat incoming calls as “data over speech”
when selected as LAN. Otherwise, when set to POTS (def), incoming
speech calls are sent to the POTS when the destination number is the
same as the POTS assignment.