Como a chamada será roteada com um LRN incorreto?
Location routing number fraud or LRN fraud works based on the desire of some service providers to avoid extra charges from LRN “dips”. Most providers will run an LRN dip to determine the correct LRN for a dialled number. However, many service providers will not perform an LRN dip if the LRN is already in the SIP message. Fraudsters take advantage of this by inserting fake LRNs into their calls. For example, they may insert the LRN for a relatively cheap terminating destination, when the call is actually going to a high cost rural destination. The service provider will then bill the fraudster for the cheaper call, but will have to eat the cost of the expensive rural call. In some cases, this can be up to five times the price they billed the fraudster.
Fonte Fraude de VoIP explicada