You can use your simcard in Israel before that make sure that your phone is unlocked. If it is locked means you need to unlock your mobile to use your simcard in Israel. To unlock your phone visit this site mobileunlocksolutions.com .

Yes your US sim will work in Australia but you will get high roaming charges. That roaming charges will depends on your service provider. If you want to avoid the roaming charges in Australia means you need to unlock your phone with current network provider. To unlock your mobile visit http://www.theunlockspot.com/supported-phones/rs10wp7/ .

you can use US  sim in Canada only if the phone in which you are going to use your sim is unlocked . if its locked to any network provider  you cant's use unless you unlock it .To unlock mobile phone visit Onlinegsmunlock.com .

Do you mean what is unlock?. If it is yes mean i will explain here. unlock is nothing but removing the network restriction from  your phone. Nowadays Most phone comes with locked status due to this it won't accept any other network  unless you unlock it .There are many ways available  to unlock phone from network lock. .Among them i would say unlock  code is the best one.If your Phone is an old model phone ,you can use free unlock code and unlock it..But if your Phone is latest Phone or I-phone you cannot get free unlock code or service to unlock it.You need to pay for getting unlocking service.You can buy unlock code for all latest phones at wickedunlock.com  and unlock it.If it's an I-phone get remote unlock service there and unlock it easily.

Unlock code is best way to unlock mobile phones from network lock.What is mobile phone brand and model ?If your Phone is an old model phone ,you can use free unlock code and unlock it..But if your Phone is latest Phone or I-phone you cannot get free unlock code or service to unlock it.You need to pay for getting unlocking service.You can buy unlock code for all latest phones at  Mobile-unlocker.com and unlock it.If it's an I-phone get remote unlock service there and unlock it easily.