Using phone in USA

[SylviaM]

I've got Volt O2 Travel Inclusive Zone, but am unsure what it actually means when it says that 

 you have the freedom to call, text, stream and scroll, just like you would at home, in 75 destinations worldwide – including the EU, USA, Canada, New Zealand, Mexico and more.
I'll be visiting the States. What network will I need to log onto there? And is the roaming on the same terms that my data usage is in the UK?
When it says that I have the freedom to call and text "just like I would at home", what exactly does that mean? Can I call US numbers without incurring international rates or that I can call UK numbers at UK rates while in the States? 
Also, I've set my spend cap at £5. Would I be advised to raise that during my time away?

[Enlli]

You can call UK numbers from the States and you can call US numbers while there.

You can use data up to 25GB in any charge period.

You should not incur extra charges.

Best reading the guide fully which gives all the information you need.

Watch they don't search your phone. Anything left wing, Pro Palestinian or anti Trump on there and you will be detained then set back.

USA - Roaming with O2 

[MI5]

@SylviaM 

Data, calls and texts are unlimited with your volt bolt on. 
Whilst in USA you should use either T-Mobile or AT&T. 
https://www.o2.co.uk/international/using-your-phone-abroad

[SylviaM]

Thanks for the advice. Do I need to dial a country code when calling either UK or US numbers when I'm in the States? Where can I find the guide to read? I'm deleting social media apps from my phone and am not bringing a laptop, so should be okay. 

[MI5 · Accepted solution]

@SylviaM 

Read the link I just posted above. 
You should dial +44 and drop the first 0 when calling uk numbers.