On January 1, 2013, all public safety and business industrial land mobile radio systems operating in the 150-512 MHz radio bands must cease operating using 25 kHz efficiency technology, and begin operating using at least 12.5 kHz efficiency technology. This deadline is the result of an FCC effort that began almost two decades ago to ensure more efficient use of the spectrum and greater spectrum access for public safety and non-public safety users. Migration to 12.5 kHz efficiency technology (once referred to as Refarming, but now referred to as Narrowbanding) will allow the creation of additional channel capacity within the same radio spectrum, and support more users. As of January 1, 2011, the Commission no longer accepts applications for new wideband 25 kHz operations, or modification of existing wideband 25 kHz stations that expand the authorized interference contour.
After January 1, 2013, licensees not operating at 12.5 kHz efficiency will be in violation of the Commission's rules and could be subject to FCC enforcement action, which may include admonishment, monetary fines, or loss of license.
Equipment manufacturers should be aware that, as of January 1, 2011, the Commission no longer accepts applications to certify 150-174 MHz or 421-512 MHz band equipment capable of operating with only one voice path per 25 kHz of spectrum. Providers may manufacture and import previously-certified equipment with a 25 kHz mode until January 1, 2013.\
To learn more, please read the VHF/UHF Narrowbanding FAQs.
Source: FCC.gov