Microsoft Teams is one of the fastest growing business products which provide internal communication and meetings, document management and integration of applications. A process of routing adopted to connect Microsoft teams with PSTN is called direct routing. Through Microsoft Teams direct routing, advantage of cheaper call rates, more flexibility and better support can be achieved. Direct routing works by combining Teams system to PSTN using two key elements, session border controller and SIP trunks. Session border controller is known as firewall for VoIP, and is used at the borders between two networks to confirm that data is properly transferred between them. It also provides a layer of security and protection from breaches and attacks. Previously SBC used to locate at premise, but, now-a-days it is cloud hosted and hence allows higher flexibility and reliability and offers lower front costs. SIP trunks are connections between a phone system of a business, the internet and the PSTN. SIP Trunks are vital component to connect PSTN to any PBX (private branch exchange).

Voice over Internet Protocol is used to send voice packages via internet, for this analog signal is converted to digital signal and then sent. But, for sending and receiving these signals, VoIP needs digital roads, and VoIP routes are the roads which help for sending and receiving voice signals. In traditional telephones, this was done by cables and using TDM technique signals used to send and receive. With increase in communication, TDM has become costly, although it had high quality performance. VoIP gives a high-quality performance at affordable cost, and user need an internet connection and a device which is usable with VoIP infrastructure whereas, VoIP providers require VoIP routes in addition to internet connection and VoIP compatible device. If there is any problem in VoIP routes, then it will be reflected in traffic, and it will cause disruptions. VoIP routes are similar to telecom routes but they are designed to work for VoIP telephone systems. VoIP packets can be sent over these routes, through internet, and this bypasses the traditional telephone routes.