Best mobile sim for overseas calls?

t8769

I often go to SE Asia, outside the EU what's the best overseas sim?

Vodafone was no good, as any use of the sim means a £6 charge for 24hs of use, even just sending 1 text
BT was no good, it did not work and was very very expensive, even if I got a voicemail and didn't pick it up, still got charged.
Who is best?
3 looks the most interesting, many countries with free or almost free service, but how does the coverage compare to Vodafone EE etc?

Thanks

Highland76

A local sim will probably work out the cheapest.

eDicky

You seem to be looking for inexpensive roaming, not overseas calls as in your title.

Three UK, in common with most networks, can roam on many or any of the local networks in a country, so there's not usually a problem with coverage.

An exception seems to be Indonesia, where Hutchison Three have a network that Three UK is restricted to (?) for roaming, and their coverage is not as good as the more mainstream networks, also limited to 2G in some areas.

It's usually easy and inexpensive to obtain and use a local SIM in SE Asia. I find that a dual-SIM handset is indispensable.