So you want to buy an inexpensive device so you can go and buy just the SIM chip? And is used ok?

I think there are some technology exchange type places. I will look. 

@ the post office they sell phones for 50sf and Yallo is intresting price.

Yes to both questions above, and thank you for looking--much appreciated!

Cool, thanks Sari!

There are a plenty of shops and online services available to get an unlocked phone. But, the cost is too expensive. Sometimes, unlocked phones are not gets unlocked in a proper manner. I have also experienced with an unlocked phone. I have purchased it via online and i inserted my T-mobile sim card with it. But, my phone asked SIM unlock code. I'm surprised ! and called them (where i have bought my unlocked phone) but, they won't give response to my call. After that, I have searched in net and unlock my mobile by using unlock code and i got it from one of the online service provider Wickedunlock.com to unlock my phone properly. Better, you can buy a locked phone and unlock it from the locked network provider of get unlocking service from any of the 3rd party service providers to unlock your mobile. Because, locked phone's price and the unlocking cost is low when compared with unlocked phones.Once, you have unlocked your phone, you can easily switch over from one provider to another without any interruption.