Belgian ISDN migration

Joined: Thu 11 of Jun, 2009

Belgian ISDN migration

Posted:Thu 11 of Jun, 2009 (21:12 UTC)
Hi, I'm new to PBX and seeking some answers, altough I know that ISDN is more a question for the european area.

Our school has a very, very, very......... ooold ISDN box called "Forum i18s". (No documentation or support found on the internet anymore)
We have 18 different phone numbers (525380 - 525398) with 18 phones attached and a separated PSTN line for our FAX.
We now got some new people into our staff and need a new ISDN box and a total of 22 phones.
Is this now ISDN BRI or PRI??

I have read a lot on Asterisk, Voip, SIP, a.s.o and also did install Asterisk as a pure Voip Environment for testing.
But when it comes to ISDN I still can't figure out wich hardware I would need to make a soft migration from the old system to Asterisk using VOIP internally with an external phone number assigned to nearly each phone.
Wich cards or other hardware do I need to connect the ISDN line to the PBX and wich cards or other hardware do I need to connect (at least 16) of the old ISDN phones to the pbx.

Idea 1) Am I wrong in understanding, that I need something like two OpenVox ISDN-BRI B800P or two Junghans OctoBri cards configured as NT to connect the old phones to the pbx
and f.e. something like a Sangoma FlexBRI to connect the PSTN-FAX to the PBX and the ISDN-outer line??

Idea 2) Or would it work (as a smooth/little migration) to yust connect one ISDN line from that "Forum i18s" ISDN Box to a f.e. Sangoma FlexBRI (new phones would be SIP only then) and buy new phonenumbers from belgacom that point to that line??
Can this be configured so that internally the new SIP phones can communicate with the other old ISDN Phones??

Idea 3) Or (yes again) would a SIPbase ISDN-Box ( be the best solution if I run the old ISDN-box and Asterisk parallel (

Begging for help and ideas (a school can pay) from Belgium, Sascha