Share your experience!
When you are in a phone call,you do not get the menu?Do you have a password or PIN?
It is very awkward,because in the call menu,you have options such as call,contacts etc.And also,you should be able to go to messages,and write.Have you restarted your phone?
I have no idea what could be causing it.I say we wait for some others to post here,see if they have something in mind.If not,I suggest reset to factory settings option.
I also use a PIN for locking my phone and during phone calls,I have to insert the pin to be able to access the phone to save a contact,to write a message etc.You are welcome,I am waiting for your feedback.