[davidtheprof]

gkeeper is not alone, I've used Piranha and generally it's fine, but there have been some reliability issues, once in Iceland and once somewhere else I don't recall. They are responsive in resolving them, but still.
Nevertheless, rates are very good, esp. for VOIP, incoming VOIP number same as GSM is great feature (using Acrobits for that), and I use it for international call forwarding even when not in a phone.
Carry a backup sim - there was a thread on this!