My Dad has just retired and is going to be travelling the globe for a few years. He wants a network that he can use everywhere.

He is aware that much of the time he will be roaming on other networks but who makes this as painless an ordeal as possible?

If it makes any difference he will be going through North & South America, Europe, Asia, Australia. Also bits within the Arctic circle i.e North Russia, Alaska, Greenland, Iceland etc.

Any help on this?

I use T Mobile when abroad – they seem to work all over. Ive used them in Nigeria, Congo, Angola, Cameroon, and they are often the only network that is available.

He may find buying PAYG SIMS in the farthest flung countries most useful, relaying his current number via group txt as it changes (Store contact details on phone, not SIM)

I use O2 across Europe because for £10 a month Its free to receive calls and costs only 25p per min to make them.

I also use prepaid data sims for my email rather than data roam which is expensive atc. £5-8 per MB. You can pre buy data from O2 which is good value if you spend a lot of time working across Europe as I do.

I suspect one of the specific international SIMs would be the best bet but have a read here

http://forums.moneysavingexpert.com/showthread.html?t=534889

I use my 5800 on 3 with skype when abroad, just find a wifi connection and im away.
Its worth looking at as an option.

I just buy a cheap phone wherever I go