The Baggies goalkeeper - an ever present in the Premier League for Roy Hodgson's team this campaign - is currently on a season-long loan from the Championship club, but Foster has given his backing to Albion's attempts to bring in Ridgewell.
Hodgson has already had two bids rejected for the highly-rated 27-year-old, but is still in talks with his local rivals over a deal and Foster believes that Ridgewell would be a fine addition to the Baggies' squad.
"If a deal can be done, I'd be very happy," said Foster. "Liam would be a fantastic signing.
"I read an interview with the gaffer who said Liam was an 'interesting' player as he can fill two positions - and that's exactly right.
"He played left-back for the majority of last season and filled in at centre-half."
Foster - who has played 43 times for Birmingham - added: "He's a great player, I get on well with him and he's someone I've kept in touch with since leaving at the end of last season."
