The Interop submenu normally does not have to be adjusted. This is only necessary if, for example, malfunctions occur when transmitting H.323 calls.
Not all ISDN implementations are prepared to receive certain standard-compliant information elements (referred to as IEs). Such IEs can be created, for example, when linking up different PABXs or transmitting H.323 calls to an ISDN interface and vice-versa.
If malfunctions are caused by the transmission of certain IEs, the gateways can be made to remove such IEs from the transmitted messages.
- Suppress Sending of HLC: No high layer compatibility information elements are transmitted.
- Suppress Sending of FTY: No facility information elements are transmitted.
- Suppress Subaddress: No subaddress information elements are transmitted.
- No Restart: Disables the automatic Link Layer connection set up in Point-to-Point mode.
- No Overlap Receive: Normally, single digit dialling (overlapped sending) is not used to call terminals (that is, devices in TE mode) on point-to-multipoint connections. Under certain circumstances however, it is possible for gateways to be connected to a PABX system in precisely this mode and then also support incoming single digit dialling (overlapped receive). In this case, an incoming SETUP message is answered, as required in the standard, with a SETUP_ACK message. Some PABXs, however, do not expect this sort of message from terminal equipment and terminate the call at this point. In such a case, the No overlap receive setting prevents the gateway from answering the incoming SETUP message with a SETUP_ACK.
- No Disc: No DISC information elements are transmitted. REL is transmitted instead. If DISC is received a RELEASE response is sent right away.
- Annex N: Allows the sending of inband information during an established call (only in TE mode).
- Volume: Here, you can set a value in decibel (db) between -32db and +32db to define the output volume to the PRI interface. Set a suitable value, if the standard value is inadequate or too high.
- CR Length: Length of encoded Call reference values in bytes. Select the size, if the standard size is not correct.
- CHI Type: When using particular protocols (for example, QSIG), you can select a different channel information IE coding type, than what the standard defines. These types are known as BRI/S0 and PRI/S1, respectively. Please note that PRI might be the right setting even on a BRI interface and vice versa.