All repeaters, gateways and other equipment operated by amateurs under licence Notice Of Variations (NOV) have a callsign. Below is a brief description of different types of NOV's, callsigns and how can apply for them.
The format of analogue FM repeater callsigns is GB3xx and digital repeater callsigns is GB7xx. This can become a little muddled with repeaters that are both FM and digital. Repeater RF links have the same callsign as the repeater with an added -L. An example would be GB7AB-L.
In the UK repeaters can only be licenced by full licence holders.
Simplex gateways can be either attended or unattended gateways. An attended gateway can only switched on and used while the NOV holder is in attendance of the gateway. The attended gateways are on 4m and 70cm. Attended gateways have a minimum level of service stated on the licensees NOV.
On the bands amateurs are primary users, 2m, 6m, 10m the gateways can be switched on at all times without being supervised by the NOV holder.
Gateways can be licensed by intermediate and full license holders.
The callsign formats are:
Attended analogue MB7Axx, attended digital MB6Ixx
Unattended analogue MB7Ixx, unattended digital MB6xx
Packet Radio Mailboxes, bulletin boards or DX clusters GB7xxx, nodes MB7Nxx. These can only be licensed to full license holders.
APRS, iGates MB7Uxx, full licensees only. Digipeaters MB7Ux or MB7Vx, full licensees. RX only iGates MB7Rxx, any licence class.
Pagers, MB7Pxx, full licensees
This information was taken from the North West Fusion Group video by G0VGS