I am installing Asterisk in a small office with just 4 lines and 8 Extensions.

I have two choices from my local telco (Fairpoint):

1) Old School ISDN BRI lines which I would connect to Asterisk with a OpenVOX B200P 2) Telco supplied SIP trunks over a service called EDIA which is 1MB ethernet over several pair of copper lines.

The ISDN BRI solution is less than 1/2 the price of the SIP solution.

Are there any risks or technical pitfalls I should worry about if I go with the ISDN BRIs ?

  • Update: My telco (Fairpoint Communications) says I can only use AT&T or MCI for long distance with a BRI ISDN line. Why am I back in the 90s ? – iewebguy Jul 3 '16 at 13:32

I can only speak from UK experience;

Risks of using BRI's:

Hardware failure. (Your channel bank)

Withdrawal of service - as in the TelCo stops offering ISDN

External PSTN Fault/failure. (but this could also wipe out any IP connectivity especially if presented over copper) but in the UK you can get total care which provides an elevated SLA for faults.

Billing - you will have to pay for CLIP/CLID etc.

Any config change requires human intervention and an order (Such as DDI numbers, or services being changed.)

At the moment I'd personally go down the ISDN route if I was installing such a system whilst it might be an 'older' technology it is very tried and tested and works well. Long as you plan your deployment and have a decent TelCo you should be OK.


From my experience, both have merit. Telco's manage ISDN call quality and your trunks are guaranteed to provide good service, CID info, etc. SIP offers lots of flexibility, but it will run over the ISP's network - and the ISP isn't worried about latency, speeds, etc.

If you can get ISDN for 1/2 the price of SIP I'd stick with that. You can always migrate to SIP later.

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