The dialer_conn process is a permanent process on the Avaya IR that is started when the Voice System starts. It listens to a specific port and waits for a socket connection to be established by the ivr_conn process on a Dialer.
When a connection is established, the dialer_conn process sends a list of scripts to the Dialer. Then, in response to a command from the Dialer, it starts a sim_agt process for each channel configured as an agent. The dialer_conn process, in response to a command from the Dialer, will also stop each sim_agt process.