We have 4 PRI's spread throughout our network and one of them plugs into the 1st T1 port on a 6509 T1 Blade. This PRI is the 1st incoming PRI from the PSTN. When this port is manually shutdown or the 6509 loses power calls into our network receive a fast busy signal. If we actually pull the PRI from the port the calls are routed to the other PRI's.
The other PRI's in our network are plugged into T1 ports on 2650's routers. They do not behave in the same way the 6509. The PSTN routes calls to the other PRI's if the T1 port is shutdown or the line is pulled.
Does anyone have any thoughts as to why these devices behave differently?
