Common materials (conductors) are:
1. Copper clad steel
This kind of wire is relatively hard, not suitable for external wire pulling, and it is easy to break the core. But buried in the wall will still be usable. And can only be used for close range, (such as corridor junction box to the user)
2. Copper-clad aluminum
This kind of wire is relatively soft and easy to break the core. It can be buried in the wall or pulled outside the wall. And can only be used for close range, (such as corridor junction box to the user)
3. All copper.
This kind of wire is soft and can be buried in the wall or pulled outside the wall. Can be used for long-distance transmission.
Among them, the only one that meets national standards is a telephone line that uses all copper