Although they have been available for many years, dual SIM mobile telephones are the black sheep of the mobile telephone market. The vast majority of mobile telephones are sold via mobile network providers, often with a discount for a contract (with the noticeable exception of Belgium, where it is outlawed).
The concept of a dual SIM mobile is simple, calls within a country are always the lowest cost when they are made via Sim card from that country, i.e. avoid roaming costs. If you regularly travel between two countries, put a SIM card (contract or pay as you go) for each country into your phone. When you make a call, simple select the lowest cost SIM for the call.
The phones work very well and dramatically cuts the cost of a call.
The challenge is purchasing a dual SIM handset, you certainly won’t obtain one from your normal network suppliers and more advanced devices such as iPhone and Blackberry are going to be a problem. That said, dual SIM handsets are available on many airlines and online, for example the E25, dual SIM tri-band phone, is currently being sold by Virgin Atlantic for £89. The phone is unlocked, so just visit a high street store at your destination and purchase a pay as you go SIM.
The E25 itself is functional but basic, think of a basic Nokia handset from 10 years ago. That said, we found it to be reliable with a very good battery life. Just one complaint, the use of colour on SMS text messages, makes them a little difficult to read.
Although the savings are attractive, particularly those for long calls or conference calls, there are problems with iPhones, Blackberrys and mobile data generally. However, given the savings on voice, a dual SIM device is certainly an option for those who travel frequently between the same two countries.