My imssg status is still for activation

It sounds as if you are not using a supported carrier. All of the supported carriers do not charge for the international SMS needed to activate iMessage and FaceTime. Check with your carrier. If they block that SMS sending or receiving, then iMessage will not activate. You can also contact Apple support. Follow the steps in this support document. If you get an error when trying to activate iMessage or FaceTime - Apple Support

Are you connected to internet with your iPhone? WiFi or cellular? Make sure that you carrier support iMessage. You could try few times, but i'm afraid that each time you will be charged for activation process.

What type of errror you got? This is usually problem with you carrier.

For example, all Serbian carriers are charging for iMessage & Facetime activation and costs are 15 RSD (0,13EUR) per activation.

That is something that would need to be dealt with the carrier. They have the right to charge for international SMS, however if they are an Apple supported carrier, they should not charge.