How to parse GPS data sent in NMEA protocol by multiple devices?

We are building a real-time bus tracking system for a client. The buses send GPS data to the configured server in NMEA 0183 protocol.

We tested the configuration on one bus. Our NMEA parser on our server is able to decode the sentences and give us the latitude longitude of the bus location.

But we are unable to verify that the data is coming from that bus itself. So, how will we detect and parse data sent by multiple buses?

via Sarfaraz Hassan