The MMS Protocol uses TCP for the connection that controls the streaming media session. The MMS server listens for incoming TCP connections from the client. Port 1755 has been registered with IANA for this purpose. Use of other TCP ports is permitted, but, in that case, the port must be specified on the URL.
If the server uses UDP to transmit multimedia data to the client, the client also uses UDP to send requests to resend lost UDP packets. Port 1755 has been registered with IANA as the destination UDP port for such resend requests.