Using Asterisk as a PSTN Gateway for OpenSER

PSTN or Public Switched Telephone Network is the collection of all the telephone networks, which are interconnected in the world. If we want to be able to route calls from and to the PSTN using OpenSER, we need to be connected to a PSTN. To send calls to the PSTN, we need a device called PSTN gateway. There are several manufacturers such as Cisco, Nortel, and others who manufacture this kind of equipment. You can also use an Asterisk PBX box for this task. Asterisk makes an affordable PSTN gateway that is very competitive with the big players mentioned above. In this article by Flavio E. Goncalves, we will see how to use asterisk as a PSTN gateway for OpenSER.