The following list describes the most commonly used interconnection types in the telecommunications industry. The list focuses on interconnection to the Public Switched Telephone Network (PSTN). The PSTN is still the dominant commercial communications network in North America. Discussions regarding interconnection tend to revolve around how service providers (not the PSTN) interconnect their networks to the PSTN. The PSTN refers to the large and small (incumbent) local exchange carrier networks. Some individuals might even include the Competitive Local Exchange Carrier (CLEC) and Interexchange Carrier (IC) networks as integral parts of the PSTN.

The following network interconnections are the de facto, standard interconnections that are used to interconnect cellular carriers, paging companies, and PCS companies to the PSTN. These interconnect types are used primarily by the LECs in their business/interconnect relationship with wireless service providers. The names have as much a regulatory and business meaning as they do a technical meaning. Not all Local Exchange Carriers (LECs) support all of the following interconnection types:

• Dial-line
• Direct Inward Dialing (DID)
• Type 1
• Type 1 with ISDN BRI
• Type 1 with ISDN PRI
• Type 2A
• Type 2A with SS7
• Type 2B with SS7
• Type 2C
• Type 2D
• Type 2 D with SS7
• Type S
• Private-line

A detailed description of these interconnection types can be found in Appendix B. The following brief summaries follow.

Dial-Line

The dial-line connection is a two-wire, line-side connection from a LEC end office. This connection is similar to the connections that are...