Just a landline cease question

[#1]

Following my connection to the PON I expected, like others, the now cancelled landline to just go silent. However, as others have reported this isn't quite what happens. Before the afternoon of ONT activation was half over my landline was cancelled - returning NU tone on calling. However, there is still dial tone on the line and 17070 returns a subscriber number based on my exchange, but with the (last four) subscriber digits changed to 8604 - which just drops out with no tone or announcement if called from my mobile. Why is this?

One thought is that immediate cancellation of a landline number is nowadays a matter of software switching to a dummy circuit number, leaving the circuit's physical connection and wiring in place, to be removed at some later date; when the landline will eventually go dead.

Could this be the answer?

[#2]

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@pvmb wrote:

One thought is that immediate cancellation of a landline number is nowadays a matter of software switching to a dummy circuit number, leaving the circuit's physical connection and wiring in place, to be removed at some later date; when the landline will eventually go dead.

Could this be the answer?

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Essentially yes, although the wiring will be left in place in any case - although when I switched, the installer asked if I wanted him to cut the physical line from my property back to the pole, which he did, and then OR disconnected it from the box on there.

[#3]

There are lots of layers here... the management of the infrastructure and the service delivered.

When a service is ceased, the user accessible service stops - the old phone number is removed from the line and the number is released to the not allocated pool.  Dialling it will give an invalid number status.

The physical infrastructure assets still have value to the network owner; the circuits (e-side and d-side) becomes available as spares to effect repairs for other users.  Leaving dial tone on the line and a circuit identifier (phone number) aids engineers in finding a not in use circuit.

The fact that the tail end might be chopped off at the property has no bearing on the status of the physical circuit.

[#4]

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@pvmb wrote:

... However, there is still dial tone on the line and 17070 returns a subscriber number based on my exchange, but with the (last four) subscriber digits changed to 8604 - which just drops out with no tone or announcement if called from my mobile. Why is this?

One thought is that immediate cancellation of a landline number is nowadays a matter of software switching to a dummy circuit number, leaving the circuit's physical connection and wiring in place, to be removed at some later date; when the landline will eventually go dead.

Could this be the answer?

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@pvmb 

Slightly different circumstances as I've had FTTP for several years and had kept my copper BT landline, but the number of which was eventually ported to VoIP with A&A on 17/9/25.  As expected, dial tone with a replacement number was present after the port.

Although it may have happened sooner, it was about a week ago when I first noticed a flashing LED on a phone I'd left plugged in which was thereby indicating no connection.  As expected upon checking, dial tone was no longer present.

Having just checked before posting this, there is no DC present on the line.

[#5]

Thanks for all the explanations and replies.