Data Only SIM + SkypeIn
I've been in London all week.
When I arrived at Heathrow I bought a data only SIM in the vending machine in baggage claim.
My friend Simon suggested I set up a new Skype account and get a UK SkypeIn number.
I did that and I have been operating without a voice connection. I use skype for voice, Kik for text, and evrrything else works just fine on data.
It's a pretty sweet lifehack. Give it a try the next time you are on the road out of your home country.