The threaddepth channel keyword controls the number of messages to assign to each delivery thread within a delivery process. To calculate the total number of concurrent connections allowed, multiply the values of the two following options: SMPP_MAX_CONNECTIONS and job_limit (SMPP_MAX_CONNECTIONS * job_limit). The SMPP_MAX_CONNECTIONS option controls the maximum number of delivery threads in a delivery process. And, the job_limit option, for the Job Controller processing pool in which the channel is run, controls the maximum number of simultaneous delivery processes.
To limit the total number of concurrent connections, you must adjust appropriately either or both of these options. For instance, if the remote SMPP server allows only a single connection, then both SMPP_MAX_CONNECTIONS and job_limit must be set to 1. When adjusting the values, it’s preferable to allow job_limit to exceed 1.