20.2.4. OpenScape 4000 SoftGate/STMIX/STMIY 
The following scenarios are supported with OpenScape 4000 SoftGate:
- Analog fax devices at Mediatrix 41xx connected to a virtual HG 3500 (SIP subscriber interface).
- Fax from central office at Mediatrix 44xx connected to a virtual HG 3500 (SIP trunk interface).
- Fax from SIP provider / OpenScape Xpression connected to a virtual HG 3500 (SIP trunk interface).
- Fax from another OpenScape 4000/HiPath 4000 system connected to a virtual HG 3500 (SIP/SIP-Q trunk interface).
- Fax from another OpenScape 4000 SoftGate, IPDA NCUI or IPDA STMI.
Each interface supports the switchover to T.38 based on tone evaluation.
INFO:
The maximal number of parallel T.38 fax channels on STMI board is 60. The limit of
60 is
independent of STMI type (i.e. whether STMI2/STMI4) or 60/120 channels, the limit
of
120 applies for SoftGate and STMIX/STMIY. Further fax calls will then be processed
with G711 clear channel.
INFO:
When using STMI4/NCUI4 boards a Fax/Modem tone detection with G729
codec is possible and the gateway will automatically switch to G711 mode.
STMI2/NCUI2 boards do not have enough performance capabilities to make
this change.
INFO:
If T.38 is supposed to be used with AP 1120, G.711 must be configured
as voice codec only, i.e. always in case a modem or fax is connected
to an AP 1120 the only allowed codec in the AP 1120 has to set to G.711
(no option for compression).