Why has my landline number changed? Please change it back!

[Mummagump]

I have just had 2 calls from someone who I thought had the wrong number.  She told me the number she had dialled which is not ours.  I phoned my mobile and this other number came up.  What has happened to our phone number and how do we get it back??

We did have a new broadband router fitted a couple of months ago but I don't know why this would have affected the phone line.  Also there is someone out there not receiving calls because they are coming to us!

What has happened?

[Mark39]

Did the installation of the new broadband router coincide with a change to your broadband service?  Does it have a 'Voice' light on the front panel?

[Mummagump]

No it doesn't, its exactly the same as the old router - we had a power surge that blew out the old router so it was just a replacement.  I'm pretty sure our old number has been working since then (this happened a few months ago) although we don't get many landline calls.