THE INTERNET

A critical piece of the VoIP puzzle is your connection to the outside world.

Before VoIP, the phone company controlled how your telecom services got to your site. They owned what is commonly termed The Last Mile—all the infrastructure right to your door. If you wanted to connect to the Public Switched Telephone Network (PSTN), you had to go through them.

Traditional connection to PSTN

 

While you can still order traditional PSTN circuits, there’s hardly any point these days. The theoretical benefits of legacy circuits are seldom realized in practice. In fact, even old-school PSTN circuits are as often as not delivered across a VoIP connection.

These days, VoIP is almost always the way to go. You connect to a VoIP carrier across your internet connection, and they in turn have switching equipment that they tie into the PSTN at strategic points (this is normally called termination, since they are connecting your VoIP connection to the PSTN at the termination point). VoIP providers make their money because they can negotiate volume discounts, as well as carry toll traffic on their own network.

VoIP Topology in the WAN

 

Your VoIP carrier will provide some or all of your telephone connectivity to the PSTN. This could be in the form of a DID and termination provider who will provide connectivity to your existing PBX, or it could be a fully-hosted system that handles all of the call control for external and internal calls, with only VoIP telephones  at your site. Regardless of the VoIP service you select, the quality of the internet connection between you and your VoIP provider will be critical.

Fortunately, since most ISPs these days also offer some sort of VoIP service, they generally do a good job of ensuring all voice traffic is carried properly on their network. In addition to this, carriers generally do a good job of interconnecting between each other as well. This is unfortunately not always the case, so be sure you use google to get a feel for how well your ISP handles VoIP quality issues. There’s lots of competition, so you hold the cards so long as you’re willing to do the research.

In some cases, you may require a premium network connection to your carrier. Generally this will be required when there is poor internet service in your area, or where your ISP does not have strong competition and they have allowed their network to degrade. In this case you will need to add the cost of an enhanced network connection to the cost of your VoIP service, and perhaps compare that to the cost of a more traditional telephone service such as PRI. (note that many PRI providers actually deliver the PRI across a VoIP connection, so make sure you get it in writing what they are commiting to deliver in terms of quality).

Your VoIP provider should be able to work with you, your network team and your ISP to ensure the internet connection at all your facilities is able to handle the job of carrying your VoIP traffic. In many cases a test or trial can be set up to validate the quality prior to committing all of your telephone infrastructure to the new solution.

If you are not sure whether your internet connection is up to the task, get in touch with us. We have tools that can help to evaluate the suitability of your connection.

THE INTERNAL NETWORK

You probably have an internal network, but if it’s going to be used for voice, a few requirements need to be considered.

Voice actually doesn’t require a lot of network bandwidth (we’ve successfully implemented VoIP phones on CAT3 cabling). A telephone call uses less than 100kbps of bandwidth, therefore a typical network connection will provide one thousand times or more bandwidth than the voice requires. What makes voice tricky on an internal network is that it has no tolerance for delayed or lost packets. Since a basic network treats all traffic as equal, a massive data transfer on the network can push the voice traffic into a situation where it’s waiting its turn. This, for users, will appear to be a system fault, as parts of what are being said end up in a buffer, or perhaps even dropped completely. The bottom line is that while voice doesn’t need a lot of bandwidth, it sends and recieves an uninterrupted stream of little packets, and pretty much every single one must be delivered, on time and in order.

Another consideration that typically comes up when evaluating a network for voice is how to provide power to the phones. You can buy a little wall plug and see if there’s a spare spot on a power bar (under every single desk in the office!), or you can deploy Power over Ethernet, which will deliver the power right through the network plug. PoE allows you to power the phones from the network switch, which will usually save you money, through not having to buy dozens of little power supplies and power bars. PoE also allows you to centralize a single source of redundant power for your phones. Connect the PoE switch to your UPS and your phones can stay on when the lights go out.

There are several strategies you can follow to address the networking needs of your VoIP project, but I would say the details all boil down to one of two approaches: 1) Build a converged network including QoS and VLANs, or 2) Install a completely separate physical network, dedicated to just the phones with simple, small-business-grade unmanaged PoE switches.

Converged Network

In a converged network, all devices on the network are managed as part of a unified, managed whole. Intelligence within the network itself determines how various devices are handled.

This method is generally sold as the technically superior way to deploy a network, but it also will tend to cost more to implement and maintain.

Larger enterprises will tend to have converged, managed networks. Smaller organizations will tend towards a simpler design.

Pros and Cons of a Converged Network

PROS CONS
Software-based management More expensive hardware
Enterprise-class architecture Higher level of technical skill required
Single cable can serve PC and phone Higher administrative overhead
Theoretically less need to move plugs More difficult for office admin staff to understand
Managed network more likely to stay neat

Generally-speaking, you’re going to look to implement a converged network if you have a highly-skilled (and factory-certified) network team, and a budget that allows for the purchase of high-end network hardware.

Running A Completely Separate Voice LAN

A simpler way to deliver a voice network is to build an entirely separate network to handle the phones. Computer traffic stays off the phone network, and voice traffic never enters the data network.

While at first this might seem like an expensive method, the reality is that in many cases it proves to be a far less expensive approach. Another often overlooked advantage of this strategy is that it is usually easier to explain to non-technical administrative staff. In my experience, this factor alone can be the deciding factor in favour of a stand-alone network.

Pros and Cons of a Stand-Alone Network

PROS CONS
Less expensive hardware More cabling required (two runs per station)
Easier to understand Separate voice and data plugs
Expensive technician not always required Phones cannot run on any port
PoE hardware can be less expensive Hodge-podge of network gear over time
Existing data equipment does not need to be touched or upgraded

CONCLUSION

The decision as to what your LAN needs in order to deploy VoIP is dependent on many factors. In general, we have found that smaller companies tend to prefer a dedicated LAN for voice, whereas larger organizations tend towards a converged network.

When evaluating the network for your IP Telephony deployment, you need to be aware of some of the differences between a hosted PBX and an onsite-PBX.

In order to simplify this, we will break the network down into two separate concepts: The Local, onsite network (or LAN), and the wide-area, external network (or WAN, typically provided across the Internet).

HOSTED PBX

Hosted PBX

In the case of a hosted PBX, all of the PBX intelligence will be located offsite. The only things located at the site will be the telephone sets, and the network components required to connect those sets through the internet to the hosted system.

Advantages of a Hosted PBX

  • No server onsite to maintain
  • Higher-quality server environment (redundant power, HVAC, internet, etc)
  • Software updates usually included
  • OPEX generally more popular with C-level execs
  • Onsite requirements can usually be handled by network team

Disadvantages of a Hosted PBX

  • Recurring costs – more expensive in the long term
  • Bandwidth requirements – desk-to-desk calls still have to pass through data center

ON-SITE PBX

On-site PBX

An on-site PBX provides all the services to the phone sets from the premises. Sets do not even require internet access, as all their requirements (provisioning files, time and date, firmware updates, security) can be handled through the PBX system.

Advantages of an On-site PBX

  • Once it’s paid for, it only needs to be maintained
  • Physical control of hardware
  • Easier termination of legacy PSTN circuits
  • Typically lower long-term costs
  • Lower bandwidth requirements

Disadvantages of an On-site PBX

  • Requires available technical team to maintain system
  • Server environment may require construction and other costs
  • CAPEX not always an easy sell to C-level execs

DECISION TIME: HOSTED OR ON-SITE?

In both cases—Hosted or On-site—the underlying technologies are essentially the same. We use the LAN to replace the traditional telephone wiring, and the WAN to replace the traditional carrier circuit (PRI, POTS lines, etc). For hosted, we additionally handle PBX connections from the sets in the WAN as well.

If you have any questions about making sense of IP Telephony, please feel free to reach out and speak to us.

The next blog in this series will look at the onsite network environment, and the considerations for a Converged versus Dedicated LAN.