5steps to successfully implementing SIP Trunk



  1. Choose a SIP Trunk provider

    There are several SIP providers and pricing will vary with the number of channels you need to support the amount of DIDs you have or will require.

    • Purchase or Port your DIDs 
      While you may already have a number of DIDs already, there are charges associated with porting those numbers over to another provider, as with cell phones. If you are not tied to the current numbers, sometimes it can be just as cost effective to simply purchase new DID’s, which can generally be bought directly with the sip trunk provider. In addition you can usually access a block of DID’s within a specific range that can help to make extension addressing more meaningful as well.
  2. Choose the server OS you will run

    • From Free PBX to Elastix for prebuilt images, these work well, and Free PBX is one of the better supported open source systems. Updates occur on a regular basis, and include most of the needed modules and GUI for the set up and future configurations.
    • Or you can choose to install any Linux flavor you desire and add asterisk and other requirements on top of that. While some companies choose to do this, the pre built images are generally pretty close to plug and play, and well supported in the open source community
    • If you are choosing a solution supported within the Microsoft environment called Lync, you will more than likely already have support from Microsoft in place to assist with any set up issues you would encounter
    • Cisco call center manager or Unified Call manager is also well supported by Cisco, and generally you will already have a support contract in place to assist in the set up and configuration.
  3. Choose the hardware

    • From the server that will run the OS, to the switch that will connect the handsets, and the handsets themselves.
    • Generally there is not a huge amount of processing power needed to run an open source VOIP system, and any physical server will do fine. Virtual Machines also work extremely well within the open source operating systems using a minimal VM configuration.
    • Switches can be PoE or just regular type switchs, the number of ports will depend on the number of handsets you will need, but typically for most small and medium business a 48 port switch is sufficient. Utilizing PoE will enable handsets to not require an outlet nearby for the power supply, however you will still require the ethernet port is close by.
    • Handsets are the life blood of the system to the end user, and are highly configurable through configuration files residing on the server side of the system. From when they ring to the type of ring, the speed dial buttons to the display the user sees on the phone. It is highly recommended to research the handsets as much as possible, while some offer excellent looking displays, speaker quality may lack, or while displays may not be as bright and colorful, the other options like speakers, and storing phonebooks can make all the difference in the world based on how they are used.
  4. Set up your Ports

    • If you are currently running ethernet ports to PC, you will also want to add additional ports for the Voice segment of your system. Or, you can choose to utilize VLANS via your switch, and purchase handset that can pass Data through to a PC. This is really a matter of preference and based on your knowledge of VLANS, I myself prefer to have the VLANS and allow the data to push through the phone as I think it provides a much cleaner look to the office space for the end users.
  5. Implement the Extension Scheme

    • Create an extension scheme that is meaningful to you or your business based on your DID block, or maybe an accounting code. On most phone systems extension start at 100 or 1000, or if you are going to use several conference rooms or ring groups, you may start of in the 2xx or 2xxx range, and hold the 1xx/1xxx for conference rooms, and ring groups. There is also the option of utilizing the DID for the extensions, such that you have a DID block of xxx-xxx-1234 to xxx-xxx-4567, you may start your extensions at 1234, and run to 4567 and enable you to assign each extension a specific DID.

The extension scheme is probably one of the most important steps in the set up, and it is often overlooked. Maybe after the fact you wish you would have purchased a PoE switch so you didn’t need those power supplies on the phones, or that you would have used VLANS instead of trying to run so many ethernet cables under the desk. But in the end, you can clean up the cables with cable ties, you can live with the power supply, but day in and day out, you will be tasked with altering names, ring groups, call forwarding, and IVR options within your system, and a solid and well designed extension layout can make all the difference between enjoying administering the system and ignoring the system.