What's the name of this film? Explain. Simple answers will not be rated.?

A (teenage / college) boyfriend is yelling angrily at his girlfriend behind a closed door saying something like "I'm sick of you!". The girlfriend says she's going to call somebody. The angry young man picks up a gun and shoots at the door. He attacks his girl on the bed in the room. I forget whether or not he was beating her, strangling her, or raping her. She desperately tries to fight back. The phone rings at another place, a woman answers, and the sound of struggle could be heard on the other end of the line. As the struggle continues, the voice of the recording can be heard "If you'd like to make a call, please hang up and try again". She weakins, unable to move. He picks up the hook of the telephone and strikes her in the skull killing her. The man takes her body, and buries in the woods. Another young man / friend of the deceased sees this, and arrives to confront him, but he is attacked. The friend is begging, the killer shoots him in the head / face without mercy.

"Shallow Grave" perhaps

Sorry, I have no idea.