Got a question for you smart lfs forumers
Im thinking about getting a dual sim phone, but i dont actually understand how they work, i mean like do both sims work a the same time? Or do you have to swap between them in os? Or do you have to restart the phone to change?

Im currently on a contract with unlimited texts, and i want to get another sim card with another company which gives me unlimited data for £5 a month.
So how would this work on a dual sim phone? Would i be able to easily write a text and send it with the unlimited texts sim, and then go straight into a web browser and start browsing with the unlimited data sim?

They usually have two buttons for calls. You can use both SIMs at the same time and you usually don't need to reboot the phone or change settings. Press the Call1 button to send messages/call/etc with the 1st SIM, and press Call2 to do the same with the 2nd SIM. On phones without two different hardware buttons for usage of the SIMs you are presented with a prompt asking which SIM you want to use for the activity you've chosen (which may be making a call, sending a text message, etc). You can also configure a default SIM to be used for some actions. I don't know about data connections on these phones, though.

Please note that the dual SIM phones are usually very (and I mean, very) inferior to the other phones, and usually made by "generic" trademarks with design based on original phones which are not dual SIM. Therefore they are cheaper, too.

Common features found in dual SIM phones in order of most found (at least in Brazil): bluetooth, TV antenna, radio (some even have the transmitter), etc. Most dual SIM phones I know don't support 3G.

I dont know much about those, but this might be useful.

http://www.cyberindian.net/top-5-dual-sim-mobile-phones/