Does anyone know how to make a UK 3 mobile 3G SIM card work in an unlocked non 3G

As far as I know there are two possibilities to get this error message "Emergency calls". One is poor signal of that respective network for which you just need to switch OFF and ON your mobile and the mobile will be able to receive the signal from near by tower. You may also get this error message when you are trying to insert a sim other than which the mobile is locked to. To solve this problem you need to unlock the phone from that particular network or use the same sim to which the mobile is locked to. To unlock your Samsung D900 you can approach Classicunlocking.com wherein they provide unlock codes at low cost. Once unlocked you can use the phone with other sim and you will not face the problem.

As far as I know there are two possibilities to get this error message "Emergency calls". One is poor signal of that respective network for which you just need to switch OFF and ON your mobile and the mobile will be able to receive the signal from near by tower. You may also get this error message when you are trying to insert a sim other than which the mobile is locked to. To solve this problem you need to unlock the phone from that particular network or use the same sim to which the mobile is locked to. To unlock your Samsung D900 you can approach Classicunlocking.com wherein they provide unlock codes at low cost. Once unlocked you can use the phone with other sim and you will not face the problem.