Seems like you should be able to program the auto-attendant to only allow a certain number of transfers, or make it require some unusual transfer operation, lik

Seems like you should be able to program the auto-attendant to only allow a certain number of transfers, or make it require some unusual transfer operation, like *8 [extension] # on Audix VMSes. A lot of Nortel ones even have the option to detect sequential dialing, and pretend anything the user dials isn't in service. That being said though, if you have access to ISUP fields on an incoming trunk, you can check and see if the JIP parameter matches an office corresponding to one of the two ANI fields, and route it to an operator if it doesn't. There'll always be a way to set your number to whatever you want, but if your number shows you're calling from a Centurylink phone in Seattle while the JIP corresponds to some random CLEC's switch in California, something is definitely up.