A SIP connection is a service that connects a company's private telephone network to the ordinary telephone system via the Internet

Simply put, SIP trunking is connecting a PBX to the Public Switched Telephone Network (PSTN) via the Internet using the Session Initiation Protocol (SIP) standard for Voice over IP.

SIP Trunking can lower the administrative burden of an organization by using the same Internet connection used for normal data, thus eliminating the need for PRI/BRI or other connections and equipment and saving the customer thousands of dollars on preliminary hardware and equipment requirements.

Dubbed "ZipTrunk™," EtherSpeak’s SIP trunking solution was originally developed specifically for ShoreTel customers but has now been ported to enables Asterisk-based IP PBX customers to make full use of their investment by connecting SIP networks with traditional fixed-line PSTN directly.  This means customers can now realize all of the benefits of IP-enabled communications without any additional investments, hardware, or even new firewall/gateway requirements.

The routing of SIP traffic to EtherSpeak’s ZipTrunk™ service is easily set up by providing three primary categories of information

• Customer information and service option selections: Billing information, technical and functional contact information and service options selections
• Technical information: Information on customer technical information, LAN subnet and firewall configuration
• DID provisioning information: Customer address information for Local Inbound, Toll-free and Enhanced Local Service, Authorization for Local Number Portability (LNP)

A VPN tunnel is required to enable ZipTrunking.  The VPN tunnel provides access from the customer's switch (where trunks are configured) to a virtual IP assigned by EtherSpeak.  The customer’s firewall must support industry-standard IPSEC encryption with availability of one-tunnel VPN license. 

NOTE: Vendors may additionally require licensing for SIP trunking to be enabled.