icm/conn_timeout is a SAP Parameter attribute which is used to control Timeout for outgoing connections information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
This parameter determines the maximum duration of a connection to an
external partner (in milliseconds). If the specified time period is
exceeded, the connection is terminated and an error message is sent to
the caller.
See SAP Parameter Documentation for full SAP documentation for this profile parameter.