The future of ISDN?

There's no direct successor to ISDN in sight. For a while it looked as if it might be ATM (asynchronous transfer mode) but these days it's all about packets (maybe ethernet) delivered by various means (copper, cable, fibre, wireless...).

If you really want reliability between defined locations you can get it at a price, in the form of digital leased lines (delivered as SDSL or whatever). Another way is having several redundant standard low-cost broadband connections from different suppliers, if available.

You might be better of switching over completely to an IP based network. If you get a highspeed connection like Verizon FiOS, it might meet your reliability requirements.

There are standards like MPLS for a more reliable transfer but I am not sure how extensively they will be deployed in the IP backbone.

-- EventStudio System Designer 2.5 -

Well, in the U.S., ISDN is alive and well, while also being 'moribund, if not fatally injured'. In other parts of the world, ISDN is the service of choice.

Speaking only about the U.S.A. (and, to a degree, Canada) --

Single-line ISDN -- aka ISDN "BRI" (2B+D) -- *is*, for all practical purposes dead.

Trunk-line ISDN -- aka ISDN 'PRI' (23B+D) -- is significantly different.

The 'alternate' technology is called "digital entrance" service. This requires that there be a 'switch' on the customer premises, to handle the digital line from the telco, and communicate with the user devices (phone handsets, or their equivalent). "Digital entrance" comes in several forms, 'ISDN PRI' being one of them. Also there is DS-0/DS-1, with either D4 or 'extended super-frame' formatting. Some telcos are even offering 'native' VoIP support.

Now, with the 'switch' playing traffic cop (and translator) on the telco trunks, one can use 'whatever one damn well pleases as the protocol between the phone set and the switch. A number of the larger swith manufacturers use 'slightly bastardized' variants of ISDn for their hand-set comm. Northern Telecom, for example, uses very ISDN-ish protocols for talking to their handsets. I believe current versions of the switch software allow use of other manufacturer devices 'behind' their switch.

ISDN BRI _is_ alive and well -- and flourishing -- in *this* environment. Just not as a 'telco offering for 'basic' service.

So, what you'll need to do for the future is: 0) 'justify' a need for 23 or 24 phone lines. (or some multiple thereof) 1) get a PBX that accepts 'digital entrance' from the telco 2) make sure it 'speaks' standard ISDN on the 'phones' side. 3) continue to use your TELOS ZEPHYR (or equivalent) gear.