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As of April 15th, CBS Sports Radio will become known as Infinity Sports Network. The change will affect the Fan 590, which airs quite a lot of the syndicated programming overnights and on the weekends.
CBS Sports features an incredible amount of American-oriented talk shows, like U.S. college football and basketball, which I don't think draws much interest in Canada. But it's cheaper than paying someone to actually do a show locally, so it's bound to continue for, you should pardon the expression, Infinity.
CBS Sports Radio to Become the Infinity Sports Network
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It’s also much cheaper to run than ESPN Radio, which TSN uses.
Rumours persist that one of both will eventually close or only run a couple of shows per day and live games rather than a 24 hour format.
I haven’t seen any such rumours about Fox Sports Radio.