Are there any exceptions to the legal requirements for signal boosters in the UK

License-exempt signal boosters are low-powered devices that minimize the risk of interference with mobile networks and can be used without a license[9]. To be license-exempt, signal boosters must meet key requirements outlined by Ofcom[2]. These requirements include[2][5]:
* No Interference Signal boosters must avoid disrupting other users' connectivity[5]. The technology should adapt to changes to minimize risk of interference[5].
* Network Safe Devices must be approved by mobile network operators, amplifying signals for the designated network without adverse effects[5]. Network-safe devices also include automatic gain control, which prevents the booster from amplifying signals beyond permitted levels[9].
* Automatic Gain Control (AGC) Built-in AGC technology prevents oscillation and maintains optimal performance by adjusting gain based on the input signal’s strength[5].
* Uplink and Downlink Shutdown The booster automatically shuts down or reduces gain in both uplink and downlink directions to prevent interference and ensure responsible usage[5].

Mobile signal boosters sold in the UK should have a CE mark, which means they comply with the relevant European Union directives and regulations, including the Radio Equipment Directive (RED)[9]. OFCOM also has a list of approved mobile signal boosters that meet their regulatory requirements[9]. CEL-FI signal boosters are the only devices that meet Ofcom’s requirements to be legal and license-exempt in the UK[2][5].