The San Francisco 49ers are still trying to work out a long-term contract with Brandon Aiyuk but also have agreed to parameters of a trade that would send the star wide receiver to the Pittsburgh Steelers, sources told ESPN.

The defending NFC champion 49ers don't want to trade Aiyuk, sources told ESPN, but contract negotiations have at times been contentious as the second-team All-Pro continues his hold-in at training camp.

Talks between the Niners and Steelers have quieted in recent days, but a source told ESPN's Jeremy Fowler that an Aiyuk trade is "one phone call away."

The Niners confirmed last week that Aiyuk had received permission to negotiate trades with other teams, but also have emphasized that there is a scenario where a deal gets done to keep the four-year veteran in San Francisco.

The situation could lead to several outcomes, including Aiyuk staying with the 49ers and playing out the fifth-year option on his rookie deal that would pay him $14.124 million. Sources also told ESPN last week that other teams are willing to pay Aiyuk more than twice as much as his fifth-year option but that he has balked so far at multiple offers.

The Browns and Patriots also were interested in acquiring Aiyuk, but sources told ESPN's Adam Schefter that New England dropped out of trade talks last week.

Aiyuk, 26, had 75 catches for 1,342 yards and seven touchdowns for the Niners last season.