Old phone, new sim

[Seahorsesailor]

I have bought a new sim for an old phone, to use for data when travelling.  Already have current sim in my everyday iPhone.  How do I activate new sim without affecting iPhone sim, do I say change my number?

[GD1]

@Seahorsesailor  A new sim has no affect on the existing old sim, you can activate through the same mobile account you placed the order with, the new additoonal sim comes with a new number.   https://www.sky.com/help/articles/sky-mobile-activate-your-sim-select-sim-type

The only time your old one would be replaced is if you ordered a replacement sim.