It's very easy to check whether Sony Ericsson Z310A phone will accept rogers sim card or not.Just insert the sim card from rogers in the sony ericsson Z310a model phone.If it accepts the sim card and continues to work it is an unlocked phone.Otherwise it asks for an unlock code or displays invalid sim card or sim not valid in the screen hence it is a locked phone.You need to unlock it.Visit the site Simpleunlocking.com/sony-ericsson-z310a/rs16wp9/ get code and get free unlocking instructions from Mobileunlockguide.com/sony-ericsson-z310a and unlock it easily.You can use any GSM network sim card from any country after unlock it.