Wireless Mics

In 2010, frequencies in the 700MHz range were phased out for wireless mics. Beginning in 2017, the FCC started to phase out frequencies in the 600MHz range.
Specifically: “Wireless microphones that operate in the 600 MHz service band (the 617-652 MHz and 663-698 MHz frequencies) will be required to cease operation sort by no later than July 13, 2020, and may be required to cease operation sooner if they could cause interference to new wireless licensees that commence operations on their licensed spectrum in the 600 MHz service band.”

However, some bands in the 600MHz range will still be available after the transition (those below 608 MHz, from 614-616 MHz and from 657-663 for unlicensed use, and from 653-657 MHz for licensed use).

You should be able to find frequency information on your mic's receiver or within the mic's battery compartment; or contact your wireless mic provider for help. The FDLC reports that Sennheiser and Audio-Technica have rebates running through March 31 for replacement microphones. Sennheiser says they will accept any competitor’s microphone for the exchange rebate.  Parishes are advised to contact the local company which installs and/or maintains your system.

See: https://www.fcc.gov/wireless/bureau-divisions/mobility-division/wireless-microphones