PAT -- please remove my email address as usual.
This system will work until individuals start setting their personal wifi units to the city's channels (frequencies) either through stupidity (defaults) or malice (you can get one for $10 these days, if you don't like your neighbors who use the city system, you could easily block them).
Remember that wifi is unlicensed (you don't need a license to have one nor or channels assigned by the government, you can use any of the legal ones at will). And since only the US Federal Government is allowed to regulate use of the radio waves.
Or even worse, the ultimate in phising attacks -- setting up a local wifi AP that tracks keystrokes and then passes the data off to the Internet.
Yuck!
- David
David B. Horvath, CCP Consultant, Author, International Lecturer, Adjunct Professor Member: ICCP Educational Foundation Board and ICCP Test Council; Chair of LPR&GC CMP