3.3.3.1.1. Requirements 
- Every station at a Mediatrix gateway must be configured as an SIP subscriber in the OpenScape 4000.
- Mediatrix 44xx gateways do not support telephony features for ISDN phones.
- Refreshing is not supported for ISDN phone displays.
- ISDN connections are only supported if Mediatrix 44xx gateways are used.
- ISDN voice connections are only supported for stations or trunks that are configured on the same OpenScape 4000 SoftGate.
- Subscriber calls (i.e. for incoming calls from Mediatrix gateway
subscribers) always have to supply their calling number (internal/extension
number).
- If the ISDN terminal does not do this, calling number insertion can also be configured in the Mediatrix gateway as required. A configuration of this kind is possible in the Mediatrix gateway (e.g. based on the ISDN port).
- The connection of multiple ISDN subscribers via an ISDN bus to a Mediatrix gateway ISDN port may not be straightforward – unless a distinction can be made between the subscribers based on call type (bearer type).