SIP Trunking Services

SIP trunking services are commonly supplied by Internet Telephony Service Providers (ITSP's) as a component of a small business phone service. SIP trunking enables them to reduce or eliminate the cost of using public switched telephone networks.

SIP trunks connect premise based VoIP PBX's to one or more ITSP's. They can support as many voice sessions as a business requires. As a result there is no requirement for a local connection to the PSTN. The Gateways are usually located at the premises of the ITSP.

As ITSP's can aggregate the collective minutes from thousands of customers they can extract a cheaper call rate from the carriers than individual enterprises and pass on a proportion of the savings.

ITSP's with extensive national and global networks can further reduce the cost of long distance calls by transferring them over their networks to a local point of presence (PoP), where they breakout. The end user incurs a local call charge instead of a long distance call charge.

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