An SMS router is a software component in a telecommunications network that manages the routing and delivery of Short Message Service (SMS) messages between mobile devices and applications. SMS routers act as intermediaries between SMS gateways and mobile network operators, and they are responsible for ensuring that SMS messages are delivered to the correct recipient.
When an SMS message is sent, it is first routed to an SMS gateway, which converts the message into a format that can be sent over the mobile network. The SMS router then receives the message from the SMS gateway and routes it to the appropriate mobile network operator based on the destination phone number. The SMS router may also perform other functions such as message filtering, message queuing, and message prioritization.