Union coach Peter Nowak confirmed the trade but says the trade is not complete on the league's side of things.
"We've been in contact every day, getting his mind to embrace the whole situation," said Nowak in regards to Califf, a California native. "He mentioned that at some point it was going to be time to go home with his family and go back to California. This will happen sooner or later. We decided to conclude this trade and that's the situation.
"It will be confirmed soon. It's not up for us to release this stuff, it's a league process. It's not our deal, it's a process we have to be involved in but need to respect it."
The Union defender has only played in four matches this season, in part because of a hamstring strain. With Califf on the way out, just four players remain from the roster from Philadelphia's inaugural season of 2010.
Unlike the trade of star forward Sebastien Le Toux, Nowak said that Califf wanted to be traded.
"For player purposes, he wants to go this way and we try to accommodate as soon as we can," Nowak said. "I'm glad we resolved this situation and he'll go back home to play with some coaches he knows. Going home is always a good thing."
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