How many numbers would an 0870 phone call have?

Question

I was rang earlier and given this number: 0870902056035258410

Part of it is the phone number and part is the reference number and I don't know which is which. Is there anyway I can figure this out?

Answer 1

It's an English number and  they are generally 11 numbers?

I reckon that: 35258410 is your reference number.

Answer 2

You can dial as many digits as you want after a working number  and it will still work, so if you dialed the whole number the far end would ring anyway.

Its going to be  08709020560 and your reference is 35258410.

I hope it's not the secret code to your Swiss bank account because a lot of people know it now

Answer 3

After the 0870 its usually 6 or 7 numbers.Try both.x