NETGEAR RT210 Reference Manual page 56

Reference Guide for the Model RT210/RT211 ISDN Routers
When an ISDN line has MSN enabled, a range of numbers is assigned to that line. The service
provider usually provides ten. A number could be from 1 to 9 digits depending on the service. The
number chosen for the router should be entered in the MSN parameter field in the ISDN Port form.
If the router does not have MSN configured, it answers any incoming MSN.
3-16 Configuring the Router