PaddyNino,
I am involved in installing BCMs in the UK. Have you verified whether your BCM200 has an onboard modem? If not, and the customer has ISDN lines (BRI or PRI), providing they are not using IP handsets, you could set up remote access via ISDN dialup.
We install various options for the customer, using an ATA connected to the modem like the other guys have mentioned, ISDN dial up, or if the customer agrees, VPN access.