A dial plan determines how calls are routed through a VoIP network. In this chapter, you will see what a dial plan contains and how to create a dial plan that points outward to the public switched telephone network (PSTN). Having multiple sites can add complexity to a dial plan (for example, because of overlapping number ranges). This chapter also covers potential solutions for such design challenges.
Dial plans typically organize a group of phone numbers in a hierarchical fashion. Consider the North American dialing plan, which consists of 10 digits, an example of which follows:
The first three digits (that is, 859) indicate an area code, which is typically associated with ...