A telephone entry systems incorporates control and communication into your gate / door .
The amount of management will depend on how sophisticated you want your system to be but basically what it does is it calls your telephone line in order for you to communicate to a person requesting access to your property.
You can have the unit call a regular land line or in some cases forward that call to a mobile device thus allowing you to take the call and allow or deny access even if you are not on the premises.
Nowadays, the development of very efficient and fast data and voice transfer rates over cellular networks make it possible to even use “cellular telephone entry systems” that work without the need of a land line and the functionality of a cellular phone.
This technology is ideal for applications where the presence of a regular Phone land line is not present or desired.