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Integrated SIP/VoIP Service

A brief tutorial on combining voice and data

Traditionally, business phone systems were powered by PRI’s made up of 23 channels or using a T1 circuit with 24 channels available for voice. The illustration below denotes the difference between a T1 circuit and a PRI circuit for voice connectivity.   Though the PRI has 24 available channel only 23 channels are available for voice connections.  A single channel is used to control the call setup and tear down, as well as receive caller ID information for each call. Using PRI circuits you have to buy 23 voice connections at a time. T1 voice connections don’t necessarily require all 24 channels being used but the end user still pays for the T1 connection and then the voice channels used on the connection on top of the circuit cost.

 

When looking at using a T1 circuit for 12 voice lines, as shown in the diagram below, 12 voice channels is used to support the voice calls.  The same holds true for allocation on PRI circuits.  Again, note that on the PRI circuit this leaves only 11 channels available to expand for other services.

To capitalize on unused bandwidth telecommunication carriers devised a means for combining Internet service and voice service on the same T1 or PRI line.  This eliminates the need for two separate lines leveraging costs to you the customer by reducing line charges.  This type of service is known as Integrated T1 or Integrated PRI service.  The following diagram illustrates the concept of using an Integrated T1 or PRI using the 12 voice lines we discussed above and the remaining channels for Internet bandwidth.  From the illustration you can see that the IntegratedT1 service provides for more Internet bandwidth than the Integrated PRI service due to the control channel used by the PRI service.  The weakness of the Integrated T1 or PRI service is that the bandwidth to the Internet and bandwidth used for voice service remains constant.  That is, if more bandwidth is required for Internet service at a given pint in time during the day even if no calls are in progress the bandwidth available does not change.  This can lead to slow Internet response time at peak times during the day.

 

The advent of Voice over Internet Protocol (VoIP) and the implementation of Session Initiation Protocol (SIP) have changed the access model and pricing structure for integrating voice and Internet service.  The illustration below highlights the use of SIP/VoIP service on a single integrated T1 Internet connection.

 

As shown in the above illustration the T1 circuit provides 1.544Mbps bandwidth to the Internet.  When no phone calls are being made all this bandwidth is available for Internet use.  However, if 12 voice calls are initiated (inbound and outbound calls) then the SIP/VoIP service reserves bandwidth for the voice connections.  In our example, assuming the SIP/VoIP service compresses the voice signal to 64 Kbps per call, then half or 768 Kbps of the bandwidth is reserved for all the voice calls in progress.  As each call ends another 64 Kbps is made available for Internet bandwidth.  This flexibility of bandwidth allows you to expand and contract the allocation of bandwidth to voice calls.  SIP trunks can be purchased one at a time, allowing your business to scale as demand dictates. The dramatic cost savings, coupled with voice quality and reliability that equals or even surpasses traditional phone providers is making SIP trunks the logical choice.  Some providers even provide SIP trunks on demand.  For example, if you purchased 6 SIP trunks for your office and there is a sudden increase in activity for voice connections the provider can dynamically add outbound SIP trunk connections to ensure your spike in call volume is covered.

What is a business SIP Trunk?

A SIP Trunk is a single voice call, routed over your Internet connection. Voice providers use your Internet connection to bring voice services to your location using this communications protocol.  Trunks are purchased according to the number of anticipated simultaneous calls in an enterprise. If you find you need more call capacity, you can simply add trunks as needed. An industry estimate is to oversubscribe the number of SIP trunks.  Using a conservative subscription you can plan on a SIP trunk for every 4 users.  For example if you have 20 people in the office the conservative configuration is to provide 5 SIP trunks to support the voice calls.  A more liberal approach is to plan for 7-10 people per SIP trunk connection.  So in our example, an office of 20 people would use 2-3 SIP trunk lines to support the voice calls.  Call Detail Records (CDR) of your current voice usage can be used to determine the best number of SIP Trunks for your office based on number of stations (i.e., phone / people) and the frequency of concurrent phone calls inbound and outbound from your location.  Broadbandcrossing.com I.T. professional services company NetworX Corporation can help with the analysis.

SIP/VoIP service and Internet Connectivity Bandwidth

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, T1 or PRI circuits.

Built-in Disaster Recovery

 If your connection fails, many of our SIP/VoIP providers can automatically re-direct incoming called to pre-defined cell phone numbers or alternate landlines.

Features typically offered with SIP/VoIP service

By serving as a converter between a legacy phone system and a company’s Internet connection, a SIP/VoIP service device allows the data network to carry voice traffic. Features typically include:

·         local and long-distance calling

·         E911

·         directory listing

·         caller ID

·         voice mail

·         hunt groups

·         call forwarding

·         auto-attendant

·         find me

·         integration with existing phone system

 For more information on SIP trunking or VoIP services go to our contact page, call us at 877.411.HSIA or why not just start the process now by going to broadbandcrossing.com,  select voice services from the drop down list  and enter your information for a quick turnaround in availability and pricing.  The service is free! You have nothing to lose.



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