My cellphone is being retarded.?

So i have the Verizon wireless LG env3 and like i've had it for awhiile now. & now it onlly works on speaker phone whenever i call someone or they call me but my friends have been telling me that when they call me, it beeps as if someone's on the other line. ): they say it happens alot. Help me on figuring out what it is and how to fix it?