SIP Trunking

SIP Trunking Explained: Moving from PSTN to SIP Trunk

The trusted old Public Switched Telephone Network (PSTN), with its Analog lines, ISDN BRI, E1, or T1 lines, is gradually being replaced by VoIP. An increasing number of businesses are using more modern and flexible SIP Trunks.

SIP trunking is a way to operate phone systems over the internet instead of using a traditional phone line. Using SIP trunking, businesses and individuals can place and receive calls from multiple clients or handsets, all of which share the same dedicated internet communications channel—the “trunk”—and all of which use the same protocol—SIP—to connect, maintain, and disconnect calls.

An internet service provider (ISP) usually provides SIP Trunking service. Unlike a PTSN provider, the lines provided are not physical but a service over your internet connection. The SIP Trunk Provider includes phone numbers and lines, usually at better rates than traditional providers, with more flexibility and shorter contract durations.

This guide explains SIP Trunks, their advantages, and how you can make a move.

Sip Trunking Press8 Telecom


What are SIP Trunks?

A SIP trunk is the modern-day equivalent of a T1 line. Where in the past you would buy a T1 line from a Telco provider and connect it to your legacy PBX, today you can buy a SIP trunk from an ITSP (Internet Telephony Service Provider) and connect it to your VoIP/IP PBX. SIP trunks use the SIP standard. The name ‘trunk’ comes from the telecom world, and it means, more or less, a group of phone lines.

Telecom service (VoIP) providers use this standard protocol to (VoIP) providers connect one or more channels to the customer’s PBX. Phone numbers and DIDs are linked to the SIP trunk. In most cases, numbers can be ported to the SIP Trunk.

Benefits of SIP Trunking

Our farewell to the PSTN brings many benefits. SIP Trunks deliver:

  • Lower monthly Line & DID Rental – The monthly fee to install several lines at your office drops significantly with SIP Trunks. And the DIDs cost a lot less.
  • Lower call charges – There are many SIP Trunk providers, and competition has driven down call charges significantly. Some SIP Trunks come with unlimited calling, and you can save on international call charges.
  • Better customer service – Provide better customer service by adding more geographical and international numbers. Quickly and easily add numbers to your SIP Trunk and terminate them on your IP PBX – you can give customers more options to dial in at a significantly lower cost, even long distance. Customers can contact you more quickly, and sales will increase.
  • Move offices and keep the same number—SIP Trunks are not bound to a location, so it’s easy to move offices without changing your stationery or informing your customers. You no longer need to pay to forward phone calls to the new offices.
  • Eliminate VoIP Gateways—SIP Trunks will eliminate the need to buy and manage VoIP Gateways. All phone calls come in via IP, and no extra conversion often means better quality.
  • Leverage a Modern IP PBX – Modern IP PBX / Unified Communications solutions will increase customers’ productivity and mobility and boost sales. Connecting an IP PBX to SIP Trunks is much easier than doing so via PSTN. You can go on-premise or host; the choice is yours.
  • Flexibility – Adding channels to your SIP Trunk can easily cope with increased calls. A simple phone call will allow you to add media, which can often be done immediately. Compare that to the delay in installing additional lines and then upgrading your old PBX to handle more lines!
  • The correct number of channels – With SIP Trunks, you can easily choose the right number of channels that you need.

Selecting the Right SIP Trunk Provider

Choose a SIP Trunk provider who will supply the necessary SIP Trunks.

A few factors come into play when making this decision:

Security – As SIP Trunks are exposed to the Internet, the SIP Trunk must have a well-secured network and an anti-fraud system in place. The anti-fraud system must monitor the design and protect against call fraud.

Own Network – Does the SIP Trunk provider run its network, or is it a rebranded service? Quite a few providers are out there reselling SIP Trunks from other providers. Select a provider who has control over their service and network.

Competitive Cost – Costs vary widely between services. Some vendors will overcharge for SIP Trunks. Look for competitive rates, but ensure that you get business-quality SIP Trunk service. For example, telecom providers will provide cheaper quality to Internet call shops. Be cost-conscious, but expect to pay more for business class service.

Number Porting – Can the provider port your phone numbers? Ensure that you choose a provider who can port all the existing numbers – not all providers can do this for all regions.

Support – Does the provider offer support? And what is their availability? Press8 Telecom has a wide range of SIP trunk providers tested and approved for use with the PBX, so we fully support them.

Upgrading Internet Connectivity

Once you have selected your SIP Trunk provider, consider a dedicated Internet line for the SIP Trunk. Most firewalls are able to handle multiple WAN connections, and, considering the low cost of an Internet line in most places, a separate VoIP connection will be the most reliable way to ensure the quality of your VoIP calls.

However, some SIP Trunk providers bundle their service with a dedicated Internet line. This keeps your voice traffic separate from your data traffic. Much will depend on the cost and your network infrastructure. Check that your firewall is up-to-date and will be capable of handling VoIP traffic correctly.

Or, Upgrading Your Current Analog PBX to a VoIP PBX

If you are considering SIP Trunks, your old PSTN lines are likely connected to another old device, the hardware-based analog PBX system. These devices are typically inflexible, difficult to manage, and often expensive to maintain. Why not upgrade to a modern VoIP-hosted PBX system in the cloud? This allows you to take advantage of the cost savings and relieves you from managing your current phone system. Press8 Telecom can provide your small business with SIP Trunks or a powerful VoIP Hosted PBX system. Call us at 800-349-VoIP(8647) or request a quote

Save money and become more productive with Press8 Telecom.

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