20.2.5. IPDA 
The following scenarios are supported with IPDA:
- Analog fax devices connected to SLMA in the host or access point shelf.
- Analog fax devices at Mediatrix 41xx connected to HG 3500 (SIP subscriber interface).
- Fax from central office connected to TDM trunk board.
- Fax from SIP provider connected to HG 3500 (SIP trunk interface).
- Fax from another OpenScape 4000/HiPath 4000 system connected to HG 3500 (SIP trunk interface).
- Fax from another OpenScape 4000 SoftGate, IPDA NCUI, or IPDA STMI.
NCUI and IPDA STMI support the switchover to T.38 based on tone evaluation
on the master call and DMC slave call.