Transferring numbers from ISDN to normal phone line and a bit more

[#1]

Hi,
I'm asking this for work as I'm a happy customer with plus.net but at present the small company I freelance for are having nothing but grief with the old firm they use Daisy Communication. 
Basically they've just moved offices and wanted their old telephone number which was on an ISDN connection moved over to the new office onto the one and only bog standard phone line there. Is this something they could do via plus.net or would they have to wait for their current supplier to do the transfer before considering moving to plus.net?
They also wanted their old fax number moved over on another separate line, and this was an 0870 number, is that something you guys could do too, or is this type of number out the realms of plus.nets net (so to speak)?
If this is all feasible then I'm going to suggest they end their contract with Daisy and sign up with you as they've already been waiting 30 days for the transfer and Daisy messed up and will now take another 30 days! Crazy I know.
Thanks in advance,
Dan

[#2]

Hi Dan,
Welcome to the forums
This is an interesting one. We used to do ISDN conversions quite a while ago (mid-noughties). As it stands, you'd have to wait until you have a standard WLR line. Though I'd imagine that Daisy may be recontracting for the privilege of doing this?
With regards to the fax, this is unfortunately beyond our realms as we cannot offer non-geographic numbers.
Sorry to hear of the problems with Daisy, hope it gets sorted soon either way
Matty

[#3]

There are various companies who'll provide porting to VOIP including number porting, but for a business I'd still retain some POTS lines (old style wired phone lines) to be available in case of IP network problems. In other words have some resilience while saving money using VOIP for routine calls. ISDN gives good voice quality and plenty of features, though you tend to pay through the nose for ISDN. Those same companies will usually provide non-geographic and freephone numbers too. The baseline is you should be able to get greater functionality than standard Business BT and never have to pay their extortionate standard rates.
Plusnet have pretty good customer support, but are not really geared up for business voice telecoms other than those with the need for two or three lines.