An unofficial voice over IP gateway that
uses multiple mobile phones and SIM cards for public switched
telephone network connectivity, while connecting to the Internet by conventional means
is termed as a SIM Box. These are normally operated covertly in third-world
calling destinations such as the "black" end of a "grey
route" where conventional private branch exchange lines like a T-carrier primary rate interface are not available to VoIP operators due to a hostile local
regulatory environment. A grey route is a telecommunication route that has one
approved end while the other end is not a legal one.
Now that we know what a SIM Box is, the next
question we face is, “What is SIM Box Gateway?” A SIM-box enables a GSM gateway functioning without inserting any
SIM cards. This feature allows storing of a bundle of SIM cards separately from
VoIP/GSM gateways in order to minimize expenses on their maintenance. The
gateways that allow a SIM Box to do so is known as a SIM Box
Gateway.
A SIM box allows one to install and manage multiple SIM cards
ranging from
20 to 300 SIM cards of different mobile operators that help
to enable the work of several GSM gateways alternately known as SIM Box Gateway, placed at
different locations. It enables one to keep his or her SIM cards away from the GSM gateway.
It allows one to attach a separate SIM card for every GSM/VoIP gateway module,
enabling the very same card to call from different points thereby reducing the
risk of blocking.
