Systems and methods for routing communications received via a PTSN are disclosed. A communication session server facilitates communication sessions between a first computing device, a second computing device and a public service accessible via a PSTN. The first computing device establishes a communication session with the communication session server using a first communication mode. The second computing device establishes a communication session with the public service using a second communication mode and a communication session with the communication session server using the first communication mode. Communications received by the second computing device from the public service via the second communication mode are routed to the communication session server via the first communication mode. The communication session server then sends the received communications to the first computing device using the first communication mode.