Using iPhone aborad

Hey Guys,

I am heading to Nepal in a few weeks. I have just noticed the call charges are £1.50 per min, and date is £6 per MB…..

I am getting the new iPhone 6 on o2, in UK. I know this has wifi calling (although i'm not sure 100% how it works). My phone will be carrier locked.

Are there any suggestions people would have on how I can avoid these costs? Or any tips? I obviously can't get a local SIM as it wouldn't work on the phone.

Or is a case of suck it up, and just use Whatsapp etc over wifi?