"There are two steps involved in the process where you're using the existing infrastructure like the towers. They might be removing a former system, so they would first of all have to decommission that [and] take any antennas or cables and systems in the wiring cabinet away. They would then fit the new antenna cables and systems in the wiring cabinet."

Upgrades also need to be made to regional management centres, according to Gregory, which manage and interoperate with mobile phone systems. This could mean new systems are required, such as security, management, operations and authentication.

Gregory estimates it would typically take one day per base station to install new systems on an existing mobile base station to fit equipment and test it. Where antennas need to be replaced, this would slow the process, according to Gregory.

Changing frequencies

Gregory says higher spectrum frequencies can be affected by issues such as high-rise buildings, which is why telcos prefer to operate around the 1800MHz or 700Mhz spectrum.