Library /sys$common/syshlp/nclhelp.hlb set, modem_connect, line, initial_hold_timer  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Default: 10                Value: 0-300

    Maximum time, in seconds, within which the control service client
    must accept an incoming call. This characteristic is supported
    only when the characteristic connection type is switched.