What is SIP Trunking?
SIP Trunking helps businesses save money by using their existing intranet or internal communication system to access the internet and outside phone lines. This system replaces a traditional phone system. SIP Trunking directs incoming and outgoing calls or data to an internet phone provider or the company’s private network.
The Basics of SIP
SIP is an acronym for session initiation protocol. Session initiation protocol gives users control over information sent from a private branch exchange (PBX) through an internet protocol (IP). The IP can be an internet address or voice over (VoIP). It also takes information from an internet telephony system provider (ITSP) and tells the PBX where to direct the information.
When communicating with a business’ PBX, the SIP:
- Keeps up with the location of each line.
- Tells the ITSP and the PBX the expected action (ring this phone line, send this busy signal)
- Determines if a line is free, in-use or unavailable
- Directs information where it is supposed to go (i.e. voicemail, call waiting, fax etc.)
- Tells a phone system which number was dialed and from where.
- Allows both systems to know when a call has ended or been transferred.
For external calls, usually a public switched telephone network (PSTN) handles these parameters for businesses and residences. Having a system that keeps up these parameters lets a business do more with their existing system without paying more.
Using a SIP Trunk Increases Productivity
SIP trunking increases productivity by adding more functions to an existing system. With SIP trunking, businesses can:
- Make calls from their intranet, including local and long distance.
- Send emails, text messages and videos externally.
- Conduct internet searches on their existing system
- Have access to directory assistance and emergency 9-1-1.
Without an SIP trunk, a company’s intranet is only able to communicate inside the company unless it uses a PSTN’s hardware (PRIs). With a SIP trunk, a company uses the VoIP to connect to outside networks using their phone system.
SIP Trunking Doesn’t Require Extensive Equipment
This service requires a VoIP phone system that understands the information provided by the trunk. Older analog systems can still connect using a SIP gateway, but the business would not get the full benefit of the SIP. SIP gateways translate information into contexts an analog phone system understands. Since the protocol provides real time data information, such as video images, caller ID or call waiting ID, businesses miss out on these benefits using analog systems.
Businesses need a router capable of prioritizing information presented by the SIP. The router not only connects the system to the internet, but it also determines what goes first — phone calls or emails. A router that sends information on a first come first serve basis does not take into account that text messages or other data are not as important in real time as conference calls.
Companies that have a PBX with a SIP trunk can use their system to connect to an ITSP. If this investment has not been made, the ITSP can host a full-featured PBX. In some cases, companies with a PBX but few users can affordably switch to a hosted PBX and avoid maintenance, monitoring and manpower required to keep up the system.
SIP Trunking Requires Three Services
As mentioned, the first service needed is anITSP. The ITSP acts as the switchboard operator. It receives and sends phone calls and data between the business’ IP address and an external IP or phone line. The ITSP also provides telephone numbers for the business.
The second service is aqualified installer. The business is responsible for setting up their internal systems. This includes getting the PBX, router and phone systems to send and receive information internally as well as to and from the ITSP.
The third and last service isinternet. SIP trunking eliminates the use of traditional public phone company wiring. Without a PSTN, companies rely heavily on their internet service for their phone and data needs.
A SIP Trunk Must Have Quality Internet Access
Without including the bandwidth savings of compression software, businesses need about 80kbps per line for optimal service conditions. Broadband services such as fiber optic or cable lines offer quality access, but pay particular attention to upload and download speeds. Often services have high speed reception, but the upload speed is not comparable.
The SIP trunk sends and receives data quickly. Slower upload speeds delays the messages and sounds the person at the other end of the line receives. In order to be sure enough bandwidth is available, companies can examine existing line usage for comparison. Since compression software frees about 30% of bandwidth usage, buying the optimal bandwidth amount allows room for growth, i.e. additional lines and services.
SIP Services Decrease Business Phone Expenses
By using SIP to access the ITSP, businesses save money. Since every phone must have a line for PSTNs, businesses eliminate the cost of upkeep for these lines. If the business has more than one primary rate interface (PRI) bundle, the SIP completely eliminates this expense. As long as the bandwidth is available, additional lines are easier to add at much more affordable rates.
Businesses save on long distance costs as most phone calls within the country are inexpensive or free, and international phone calls cost less than most PSTN fees. The SIP trunk connected with an ITSP provides more features than PSTNs without additional costs. Here are a few of the services this system provides that PSTNs traditionally charge for on a per-line basis:
- Voicemail
- Caller ID
- Call Waiting
- Dedicated Fax Line
- Extensions
This protocol improves scalability by taking away the 23 voice channel increments and eliminating PRI maintenance costs. Virtual telephony services offer built-in resources for redirecting calls during internet outages or other disasters, which makes disaster recovery plans implementable. SIP trunking is transferring the way a business accesses the outside world from physical to virtual connectivity.