
For now on, users must seek the permission of carriers. Even the 2 million devices already in use must be turned off immediately unless their owners register them. The FCC states in an FAQ:
Did the FCC recently adopt new rules for signal boosters?
Yes. The FCC recently adopted new rules to improve signal booster design so these devices won’t cause interference to wireless networks. The FCC also adopted new rules about what cell phone users need to do before using a signal booster.
I already have a signal booster; do I need to do anything under the new rules?
Yes. Under the FCC’s new rules, you (1) need your wireless provider’s permission to use the booster, and (2) must register the booster with your wireless provider. Absent your provider’s permission, you may not continue using your booster.