[Freeswitch-users] Stripping Leading Digits of 10-digit Inbound Number

I am using a Sangoma PRI card. When an inbound call is received, where do the leading digits get stripped off? For example, if the inbound called number is 4257405381, I notice the call is routed to 5381 extension, but I don't know what is stripping off the 425740 digits. Best Regards, Jerry