Jacob Woodford had been staying at holiday camp in Selsey on September 8 last year.
He called 999, claiming to have a sawn-off shotgun that he would use to harm himself.
During the phone call, he also made a false claim about having a hostage tied up inside the caravan.
Armed response officers and police negotiators attended the scene, and after a one-hour stand-off Woodford surrendered and was arrested on suspicion of making threats to kill.
The 29-year-old, of Benhams Road, Southampton, was charged with sending a communication conveying a threatening message, under the Malicious Communications Act, and admitted the charge in court.
At Portsmouth Crown Court on July 8 he appeared for sentence. It was revealed he had committed the offence just one month after being given a suspended prison sentence for assaulting a police officer in Hampshire.
Woodford was sentenced to a total of ten months in prison for his offence and for breaching his suspended sentence.
The court heard how officers had earlier attended the holiday park at 6.42pm and arrested a person known to Woodford on suspicion of assault. The person was later released without charge.
Woodford then admitted drinking vodka and mixers before he later called to demand that the person was released from police custody, threatening to take his own life.
During the 999 call, he claimed he had a firearm and said he was going to kill any officers sent to respond to the incident.
Then he claimed: “I’ve got someone here, he can’t speak right now, he’s tied up.”
Woodford eventually agreed to surrender to police, and during his interview he apologised for his “drunken mistake”.
When officers searched the caravan where he was staying, no weapons were found and there was no evidence of any other person being inside.
Detective Sergeant Chris May, from Chichester CID, said: “Woodford’s drunken 999 call caused great concern.
“Our contact handler acted professionally to keep him calm and gather important information, but Woodford continued to escalate the situation by making threats to harm himself and others.
“The offence he committed was less than one month after he had received a suspended prison sentence from West Hampshire Magistrates’ Court for assaulting a police officer.
“His threatening phone call needlessly put himself, our officers, and other members of the public at risk.
“It also meant that specialist officers could have been prevented from attending a potentially critical incident elsewhere while they responded to him.
“We are pleased with the outcome of this case. It demonstrates our determination to prosecute offenders who put the public at risk.”