What is a SIP Trunk?
A SIP Trunk is primarily a concurrent call that is routed over the IP backbone of
a carrier using VoIP technology. SIP Trunks are used in conjunction with an IP-PBX
and are thought of as replacements for traditional PRI or analog circuits. The popularity
of SIP Trunks is due primarily to the cost savings of SIP, along with the increased
reliability as backed by the SLAs of SIP Trunk Providers.
What are the advantages of SIP Trunks versus Analog Circuits?
SIP Trunks are cheaper than analog circuits while maintaining the same service quality
that businesses expect from line quality. SIP Trunks cost approximately $20 to $30
per trunk, versus $40 per analog circuit. In addition, long distance termination
charges associated with SIP Trunks are much cheaper than traditional analog or TDM
rates.
What are the advantages of SIP Trunks versus PRI?
SIP Trunks realize their primary benefit over PRIs from cost savings. SIP trunks
typically cost $20 to $30 per trunk for unlimited inbound and local calling along
with a long distance rate that can be under 2 cents per call. When coupled with
line oversubscription (e.g. a 30 person company purchasing just as many SIP trunks
as they anticipate having concurrent calls....typically 8 to 10) SIP Trunks are
a very cost effective way for a business to save money. Lastly, a primary benefit
of SIP Trunks over PRIs is that SIP Trunks can be purchased in increments of 1,
whereas PRIs have to be purchased in increments of 23 channels.
What equipment do I need to be able to use SIP Trunking?
SIP Trunks can work with a SIP-ready PBX. SIP Trunks can also be made to work with
traditional analog or key systems with an IAD (Integrated Access Device). The SIP
Trunk service provider will need to interoperate with the underlying equipment manufacturer.
However, it should be noted that with the advent of standards around RFC 3261 and
SIP Connect, the challenge of finding SIP Trunk Service Providers with SIP Trunk
compatible equipment is significantly decreased.
Will I need more Internet bandwidth when I buy SIP Trunks?
SIP Trunks are virtual circuits delivered over an Internet Access line. Depending
on the number of SIP Trunks purchased, and the amount of excess Internet connectivity,
a business should consider purchasing more Internet Access. However, it's important
to know that when a SIP Trunk is not being used, the bandwidth otherwise allocated
to a SIP Trunk is freed up for use in less intensive applications, such as e-mail
and general web use. This dynamic allocation of bandwidth is yet another feature
of SIP Trunks versus more traditional technologies, such as analog or PRI circuits.
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