VoIp and Direct Inward Dialing (Did)

Home phone set ups are wholly distinct from those found in a business. Of course, there's nothing which says we can't use the same setup, but due to the way a business functions we can make many components more efficient. One of these components is the corporal line that comes into the office. With home phones, we need a separate line for each new telephone and telephone estimate in the house. This makes sense since each estimate "owns" that line and when an face person dials it, there's no problem with figuring out who the call is for.

Businesses with potentially hundreds or thousands of employees in the same office simply can't afford to have so many lines arrival in and out of the building. It's not just the cost but it's ineffective as well. So the telcos (starting with At&T) developed a technology called "Direct Inward Dialing" or "Did" which allowed the same set of wires to be used for manifold phone lines. This required the business to take the accountability of forwarding the estimate to the literal, person and this was done using a Pbx.

Att Call Conference

We've seen old movies where an attendant manually switches calls to the right person and over the years we've evolved to a theory where all that can be done automatically. The telephone business lets the businesses Pbx know the estimate it has to connect to by sending the last few digits to it which is unique to every worker within that business and the Pbx connects it up automatically.

This has great relevance to VoIp which relies on tight integration with the Pstn network in order to function. At a technical level, every Sip VoIp user can be identified by their Sip address which goes something like "userabc@serviceproviderxyz.com" - like an email address. But that's not what regular users need to sense you and it's admittedly not what you'll put up on your website. Like everybody else, you will need a regular telephone estimate which habitancy can dial and which will ring your VoIp phone. This is nothing but the technology of Direct Inward Dialing or Did.

Strictly speaking, you don't need Did in order to make a telephone call - only to receive it. But users won't know who's calling if you call them directly from your VoIp phone without an related estimate and that might put habitancy off. In most cases you won't even need to know about terms like "Did." Your VoIp victualer will give you a estimate automatically.

VoIp and Direct Inward Dialing (Did)