An attacker told his pensioner victim to phone the emergency services and warned "you're going to get it" before leaving him unconscious and covered in blood.
Gareth Wetherell had turned up at the 67-year-old's home unexpectedly in June last year, when the victim was asleep in bed, but was invited in for a drink.
Newcastle Crown Court heard the 28-year-old boasted he had been taking drugs and seemed "high as a kite".
Prosecutor Rachel Masters said it was during a conversation about a historic murder case that Wetherell became "raging" and launched the terrifying attack which left the pensioner unconscious with a fractured bone in his face.
Wetherell stole his unconscious victim's phone before he left the house, which meant he was not easily able to summon help.
Miss Masters told the court: "The defendant repeatedly shouted at him then handed over to him his phone and said 'phone an ambulance and the police because you're going to get it'.
"At this point he was extremely scared and repeatedly asked the defendant to leave."
The court heard during the violence that followed, the victim was punched "full on" in the face three times and hit in the ribs.
Miss Masters added: "He fell unconscious, felt as if he had been knocked out.
"He woke up, covered in blood and the defendant had gone."
The court heard the victim had to struggle outside to call for help when he realised his mobile phone had gone.
He was taken to hospital with a fractured bone under his eye, with significant bruising and swelling, and abrasions and soreness to his ribs.
The victim told police in a statement: "I have never been so frightened in all my life. The fact he stole my phone left me vulnerable and isolated.
"Him knocking me out has knocked my confidence.
"I am petrified of him, what if he hits me again?"
Wetherell, of Windermere Crescent, Shiney Row, Houghton, admitted causing grievous bodily harm.
He was found guilty of theft of the victim's phone after a trial at magistrates.
Mr recorder John Thackray sentenced him to eight months behind bars with a five year restraining order to keep him away from the victim in future.
The judge told Wetherell: "You told him you were going to assault him, you told him he needed to ring for an ambulance.
"You had plenty of time to calm yourself down but you chose not to.
"You are a very large, fit and powerful young man.
"He became unconscious. He woke up, covered in blood, you had stolen his telephone and he had a fracture to his eye socket.
"He was entitled to feel safe and secure in his own home, not be attacked by you."
Charlton Carr, defending, said Wetherell is a self-employed ground worker who supports his family and is full of remorse.
Mr Carr said: "He would say it was a spur of the moment matter that happened when fuelled with drink."