Traditionally, telephone numbers relate directly to end points on the network. A fixed telephone line's identity
is its number, and it is at a fixed location. Similarly, a mobile phone has a particular identity, which is associated with the SIM card.
We all agree that, on the basis of the above, the numbering plan of 01/02 numbers being for fixed lines and 07 numbers (some excepted) being mobile-telephone 'lines'.
In both these cases, it is possible to
route calls
onwards with call diversion. This passes calls on to another PSTN number, for which the end user (the one who has set the diversion) must bear the cost of the diverted leg of the call.
In many (not all) practical circumstances the diversion (on the incoming number) can be set, modified or cancelled only from the respective telephone (endpoint). What this means is that in order to set, modify or cancel a diversion on a fixed line one will usually have to be present at the location of the line, and similarly to do likewise with a mobile telephone service, one will have to have the mobile phone with battery power and signal available.
Thus, calls
always come in to the particular phone with diversion being something
extra that can be set. In real terms, the call doesn't actually 'come in', of course, but in effect the diversion can be pictured in the mind as being just that.
By contrast, VoIP is different. A VoIP account has an incoming number but this number has no association with any particular end point (to which it 'comes in'). In this respect, e-mail addresses have always been the same, and this a good comparison to draw. An e-mail address isn't associated with any particular endpoint.
So, why should a telephone number be associated with a particular endpoint? The answer is that it doesn't have to be, although this is how telephony began and has grown up.
As the popularity of VoIP increases, as I think it will, the association of endpoints to particular incoming numbers (as identities) will tend away. In reality, the majority of VoIP providers are offering service with 01, 02 and 03 numbers, along with other 08 non-geographic numbers (I'm not sure about 09).
Compare the traditional notion of a number associated with endpoint and a number associated with a person (a person's VoIP account). The latter does everything the former does and more; thus, it follows that the reverse must also be true: the former is more restrictive than the latter. Or to put it another way: the functionality of the former is generally fully encompassed by the latter – the reason that the former is king is down to evolution. While on the one hand we might expect a natural tendency to VoIP, this will be countered by the might of the providers of conventional voice telephony.
A mobile telephone number is generally regarded as a
personal point-of-contact, as opposed to a geographic number being for a fixed point on the land. But it still is associated with a particular endpoint, requiring connection to a particular network and particular hardware to be available. By contrast, VoIP is network-neutral and can be delivered on whole manner of different hardware – the prerequisite of association with endpoint does not apply.
The crux of my point is:
- (Rhetorical question) Where might the increasing move to VoIP leave the numbering plan, in terms of having destination types classified by number prefix?
- The need for a number to be associated with a particular location is likely to tend away with the growth of VoIP. After all, if a landline number is delivered to the end user by VoIP, the intricacies of diverting to a mobile do not apply – calls are received as data choose whether in a fixed location or mobile.
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Ofcom's changes to 070 numbers. (Read 31,194 times)
