CMS does not support ISDN. To make ISDN calls, you need a gateway
The ISDN GW 3241 is the latest gateway available, there is no ISDN alternative (other than endpoint-based ISDN link), the recommendation is to move to SIP based solutions such as Expressway.
simple answer is. Check CMS datasheet and if it supports ISDN protocol then it will work otherwise you need a gateway to translate ISDN calls to SIP calls.
to my knowledge it does not support direct termination of ISDN calls.
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