Dual SIM Cards
By MortazaviBlog on Oct 16, 2005
If you pay large roaming fees and travel mostly between two geographic locations or, there might just be a solution that fits well to your needs.
Many believe that GSM phones can only operate with a single SIM card or a single mobile number. Others think that full-blown IMS is necessary to reach a single physical end-point through multiple numbers. Well, both of these beliefs prove to be wrong. Let's tackle the first one.
International Herald Tribune has a business description of dual SIM cards. The report blames the operators for preventing the wide-spread use of this technology. Two reasons are given. Operators do not want to share their subscribers with others. Operators do not want to be responsible for phone-related customer support issues that might have arisen because a phone with dual SIM might have received corrupting bits while attached to another operator's network. Both of these are relatively reasonable explanations. The dual SIM phone needs to be turned off and on in order to enable one or the other SIM card—not very practical unless you want to use it while traveling. Of course, another choice (if you like to have separate phone numbers for work and family matters) might be to attach two numbers (subscribed from the same operator) to the same (single) SIM card. Most GSM operators offer this service. The advantage here is that the phone car work with both numbers for incoming calls without having to turn it off and on. On outgoing calls, there's a primary number that is used. To use the other one, an access code might have to be dialed. With a bit of programming, some phones can have an even easier interface for this.