Link old%20number%20to%20apple%20watch

[Ahhhhh]

I just bought a new iPhone and Apple Watch series 5.. I want to keep my old number and I have the PAC number...BUT...

when I ordered the watch i had to link it to the new iPhones existing number. It was the only option available.

if I use the PAC and use my old number, will the Apple Watch still work with the new phone? Does it pair to the phone or the phone number?

im hoping not to have to change to the number as I'm self employed and changing it now would be a logistical nightmare!

what about if I lost my phone or upgraded and changed numbers, would my watch become obsolete?

thanks in advance for any help!

[MI5]

@Ahhhhh 

The data plan is linked to your O2 account for your iPhone.

If you leave O2 you will have to setup a new data plan with your new provider for the watch.