He will return to St. Andrew's should City be promoted, but that is looking unlikely after a mass exodus of players and an average start to life in the npower Championship.
When asked about his future, Foster said: "I honestly haven't got a clue. As far as it stands it was just a season-loan deal and that was that.
"It just depends on what happens at the end of the season.
"If Birmingham go and get promoted and get back in the Premier League then I will be back there playing football with Birmingham - simple as that.
"If it doesn't happen, then there is a decision to be made on both parties.
"It's out of your hands to a point. I will have to bide my time and wait and see."