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 (ShoreTel in this case) to the Public Telephone Network via the internet using the SIP VoIP standard.

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.

EtherSpeak’s SIP trunking solution, developed specifically for ShoreTel customers and dubbed "SureTrunk™," enables customers of all sizes (ShoreWare-based IP phone systems) to make full use of their investment by connecting SIP networks with traditional fixed-line PSTN directly.  This means ShoreTel 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 SureTrunk™ 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 ShoreTel 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 SureTrunking.  The VPN tunnel provides access from the customer ShoreTel Switch IP (where trunks are configured) to a virtual IP assigned by EtherSpeak to the customer’s ShoreTel switch.  The customer’s firewall should support industry-standard IPSEC encryption with availability of one-tunnel VPN license. 

ShoreTel requires licensing for SIP trunking to be enabled.  Your ShoreTel reseller can provide information on purchasing the required ShoreTel SIP trunk license.