Transferring number without a line cease

[#1]

Hi
This isn't a Plusnet Home Phone query, but I'd more than welcome Plusnets thoughts on this as well.
We've just set up a Multi User VOIP system with Gradwell, and will have our BT number ported into the VOIP system tomorrow.  When porting the number to Gradwell the BT line that the number was on is ceased (as we expected).
What I am now thinking of doing is porting in 2 other numbers for other phone lines (one AOL and one Utility Warehouse I think), but would like the phone existing phones lines renumbered and the line and broadband on it to continue.
The purpose for this is that the numbers on both of these lines are in the public domain (a vicar and a curate, did I mention this is for a Church!), so want those numbers in the VOIP system, but would want a new number for each of them on the existing lines which they can use for private use, and then the old numbers, now on the VOIP system, for their public duties.
This will all be simple enough from the Gradwell side of things, but I have no idea if it could be done on the PSTN side of things.  I'm asking here as it's a friendly place with plenty of knowledgable people around who might be able to say if it is worth trying to get AOL and Utility Warehouse to do this, or if I will be on a hiding to nowhere!
Thanks
Phil

[#2]

Phil,
Are you just asking if the PSTN lines can be renumbered?
If so, then yes they can, but you may have to pay an admin fee.  We are charged £35.85 as a Wholesale charge to do so.

[#3]

Thanks James. I think it is as much could we do a renumber and a number porting on the old number at the same time, or would the line have to be ceased at the same time as the port?
Thanks
Phil

[#4]

In order to port a number into VoIP you need to be able to demonstrate 'ownership' of the number. I suspect that as part of any renumber, you would lose rights to the old number.  I would have thought Gradwell may have some ideas of whether it's possible to do what you want. I'm sure you can't be the first person who wanted to do something like this.

[#5]

Thanks MisterW.  I was going to have a chat with Gradwell about it at some point.
Thanks
Phil