I was recently involved with a setup that integrated an Ericsson BP250 PABX with an Asterisk installation by means of ISDN PRA (Primary Access). The purpose was to use the IP capabilities of the Asterisk PABX while continuing to use the current telephony interface and telco access present on the Ericsson PABX. Thus the telecoms provider continues to be terminated on the Ericsson PABX. Also, current users are not all migrated to the Asterisk. Then a QSIG link is established between the Ericsson and Asterisk PABX's, allowing the two PABX's to integrate transparently. Setting up PNR's worked effectively, with the entire destination number as the directory number, and no predigits added or removed.
For a stable link, please note the following:
Ericcson:
Place the network card in the first cabinet for improved timing.
ISDN PRA link = Q I/F
Protocol = ETSI
Termination = Master (layer 1 master) - note, no modem exists between the two PABX's.
CRC = CRC permanently disabled.
The rest is on default.
Asterisk:
Protocol = EuroISDN
Signalling = PRI CPE (Internal)
HDB3
