just upgraded to iphone 6, cannot send or recieve texts

On my iphone 4s I had difficulty sending and recieving texts due to not enough memory, people kept sending me pictures and my phone could not download the pics. The texts would freeze my phone. I could delete apps and then recieve the pending texts with pic.

I upgraded to 64 mb iphone 6 to avoid problems with memory. I cannot send or recieve texts freely. About once a day, I get one or two texts that someone has attempted to send me several hours earlier. At that time, I am able to text them ( or even someone else) back once or twice until my phone freezes during the sending phase of the text. It remains that way in "sending" mode until i turn my phone on and off again.

I have reset the iphone 6 once.

I have reset the network multiple times in the last 2 days.

It doesn't matter if its imessage or sms text, neither work properly.