Using my phone in the USA

[CH-1]

I am currently on a monthly rolling plan, what charges will I incur when using my phone in the USA and what bolt on could I purchase? Thanks 

[pgn]

Rolling Plan implies you are on PAYG using a card to permit O2 to take your payment every month, correct?

So you have no means of using your phone for texts or calls when in the USA, as O2 does not permit the use of "4G Calling" on PAYG. USA - Roaming with O2 WiFi will only work cost-effectively when latched to hotel, mall or eatery WiFi. Your best bet is to buy a local PAYG SIM for use when out and about to get a data connection, then use something like WhatsApp for you and friends and family to stay in touch - both parties need to have the free WhatsApp app installed. Everything Elsa will be too awkward, or costly, to use, @CH-1. You can buy US PAYG SIMs from Amazon and then activate it upon landing Stateside.

https://www.o2.co.uk/international/using-your-phone-abroad

[CH-1]

Thank you for the advice, i am indeed on the PAYG will with O2 taking an automatic payment every month.

[pgn]

The Amazon US SIM option with a fair chunk of data works the best for PAYG, speaking from experience of a 3-week stay in Florida recently, @CH-1  👍