I guess that kinda brings up a new trivia question: If iHeart changes the calls from WISX, it will be the eighth set of calls to have lived at 106.1 FM (following WQUAL, WWSH, WZGO, WTRK, WEGX, WJJZ, and WISX). Is that the most of any Philly FM?
If you count a basic call sign with and without the -FM suffix separately, you can get 96.5 and 104.5 to eight.
96.5: WDAS-FM, WHAT-FM, WWDB, WWDB-FM, WPTP, WLDW, WRDW-FM, WTDY
104.5: WJMJ-FM, WRCP-FM, WSNI, WSNI-FM, WYXR, WLCE, WUBA, WRFF