How to manage mobile telephony abroad? Here are my approaches and my various discoveries on the subject, abroad. In some countries, there are interesting international offers (good value for money) but this was not really the case in Switzerland when I left.
Getting rid of a mobile subscription when leaving abroad
Contracts are often long, and have rather discouraging termination terms. For example, my company (Sunrise Switzerland), despite 13 years of fidelity, has put a lot of obstacles in my way. You are given ten different versions for each call from the head office (it's the same thing in the shops) and you are asked to pay a hefty fine for a termination out of time (215€, anyway).
In the end, you can find out that if you provide official proof of more than six months' notice, you get a free termination. But couldn't they have said so earlier? Nothing new under the sun, it seems to me, we don't like to let customers get away. However, the so-called "we didn't get your letter", and other voluntary wastes of the company's time, are to be expected, prepared for, and therefore taken in advance.
So I contacted the foreigners' police to obtain a departure permit for more than six months (this is the usual procedure for holders of a work permit without a Swiss passport) and I was able to forward the nice paper I obtained to the phone company.
Cost of the operation: about 50€ (authorization + signature letter) and a lot of trouble... For Swiss citizens, it seems to me that the municipality can issue such a certificate. For you other French, Belgian, etc., please ask the commune where you are domiciled.
Getting SIM cards everywhere abroad
Mobile telephony in Europe
For some years now, EU citizens have had the opportunity to access roaming at no extra cost in all member countries. A bargain! You no longer need a card for Germany, France and all other countries where you travel more frequently. I have acquired a prepaid SIM card for Germany (from Vodafone), with a flat rate of 9.90€ which gives me access to 2Gb of data, including abroad. You can check
simoptions.com and learn further more information about using prepaid SIM cards abroad.
Mobile telephony in Asia and elsewhere in the world
For countries outside the European Union, and this regardless of the length of my stay, I acquire a new chip for my mobile phone. Since a few years, you can find them directly at the airport! In Bangkok, for example, there are a few providers (inside and outside) and you can compare the different offers... If you are patient, you can wait in the queue.
The costs are very often very low, both for departure and communication. For example, in Sri Lanka, a prepaid SIM card will cost around 200rps (with 150rps talk credit). Add 99rps and you get 400Mb of data. In total: about 2.20€ of spending, and you can call services, hostels and friends without worrying about the ridiculous price of the calls... And at worst, you buy a 100rps top-up, ~0.75€, and you're good! For a 1'000rps (~7.30€) top-up, you can phone for about 15 minutes in Europe. The topo is more or less the same everywhere in South-East Asian countries.
For other countries, it will unfortunately cost you a bit more (as for example in Turkey where my package cost me a bit less than 20€ whereas I only spent a week there). It's up to you to see if free wi-fi is enough for you or if you want to have immediate access to the net, everywhere!
The prepaid card from your country of origin, a safety net
Always make sure that your primary SIM card is activated and allows sending SMS messages and calls at a minimum, or even data. In the event of an emergency or problem (flight cancellation, communication problems with your hotel, etc.), if your local card does not work or if you have not yet purchased one, you will be happy to pay a small fee for the convenience of making a call!
Where to get a SIM card abroad
In the end, all this helped me a lot: the system works pretty well and doesn't make a hole in the budget! On the other hand, in some countries, getting the SIM card can be a real time investment.
In Sri Lanka for example (it was the case in 2010, things may have changed!) future subscribers had to show an identity card... from Sri Lanka. You will certainly find a Sri Lankan willing to help you, but this usually comes at a price. This can lead to some rather peculiar situations... and a lot of wasted time, between haggling and misunderstandings. I ended up going to a center of the communications company in question, and no problem. In other countries you can buy a SIM card in a shop and activate it yourself (e.g. in Barcelona). It's up to you to see what you prefer to try! I like the phone brand stores better and I ask for it to be activated on the spot, so that I can be ready immediately and don't have to come back the next day.
In short, if you don't count, you can easily get what you want quite quickly (beware though, they tried to give me in Sri Lanka a card used for a price ten times higher than the local one, and they also sold me in China a SIM card that didn't work with my mobile, even though they assured me that it was the case... and then they didn't want to refund me, I just had to know myself, here)!
So the best thing to do is to always ask the people in your guesthouse or accommodation, or in a place that seems nice (and not too interested) before starting the SIM card race!