+1 in suggesting an eSIM.
iD have 2 roaming partners over the pond, but anything you do with your phone is chargeable. So whilst in the USA, for you to make calls or texts or check your apps from there:
Roaming | Pay monthly | Pay-as-you-go**** |
---|
Calls to UK* | £1.68 | £1.68 |
Calls to United States (USA)* | £1.68 | £1.68 |
Calls received* | £1.50 | £1.50 |
Texts to United States (USA)** | £0.42 | £0.42 |
Texts to UK** | £0.42 | £0.42 |
Picture message (MMS) sent** | £0.60 | £0.60 |
Internet and Data (per MB)*** | £0.30 | £0.30 |
* Price per minute
** Please note: MMS charges vary. For further information, refer to Terms & Conditions. If you joined or upgraded on or before 20th June 2023 the MMS cost is £0.30 per message for Roaming within EU Bands 1 and 2.
*** Data is charged or deducted in one kilobyte (KB) increments and any part KB used will be rounded up to the nearest KB
**** The charges below will apply to all Pay-as-you-go customers starting from 1st October 2024. Find out more about the current charges here.
Prices shown include VAT where applicable.
I’d also suggest nudging the billing cap to £0, turn off roaming via the app and set your phone to manual network selection PRIOR to leaving the UK. The latter should prevent accidental connections to roaming connections.