Cell phones can be locked using a SIM lock capability built into GSM phones by mobile phone manufacturers. Most network providers (such as AT&T, Vodafone, T-Mobile, and RIL etc) use this capability to restrict the use of these phones to specific countries and network providers. Generally, phones can be locked to accept only SIM cards based on the International Mobile Subscriber Identity.
Each Mobile Subscriber Identity is mad of the following
- Mobile country code so that SIMs issued in one country will work.
- Mobile network code.
- Mobile station identification number.
In other words localed phones cannot be used with other network. You are restricted to a single carrier’s network. For example, if you buy a cell phone from a network provider such as Sprint, Cingular, and, Verizon, etc the phone is locked to their network, so you cannot take your phone and sign up on a different network. You cannot insert other SIM card and use it.
What is an unlocked cell phone?
An unlocked GSM phone is not locked into a single carrierâ€™s network. You are free to insert your active GSM SIM card into any unlocked phone and start using to send text message or make a call.
How To Save Money With Unlocked Phones?
- First, get a cell phone that supports tri-band (or get quad-band if you are going to use it in Asia or Europe). Make sure it is unlocked one.
- When you go to Asia (for example, India or Japan) or Europe (UK etc), purchase a new local SIM card. Do not use your own sim card.
- Insert local sim card to make local and international calls. You will pay International rates to call home and local rates for local calls.
- If you use your own sim card you will pay International rates + a roaming charge. By using local sim and unlocked phone you can save tons of money.
- Unlocked cell phones are 100% legal in every country. In fact most cell phones in Asia and Europe are unlocked. You can pay as you go and change your SIM card whenever you want to go!
- Most CDMA providers such as Verizon, Sprint, and Alltell all use CDMA which do not use SIM cards. In others words unlocked phone will not work with them.
- Some cell service provider (such as Verizon and RIM) do not use sim cards. If in doubt ask the cell service provider and they will give you exact answer.
- Unlocked phone costs big bucks as there are not contracts.
- All unlocked phone should work well with any carrier in the world that uses SIM cards.