VoIP and Hosted PBX services require a certain amount of bandwidth in order to keep your conversations clear and free of disruptions.  Bandwidth is the amount of information which your internet connection can send and receive in a certain period of time.  Your first step should be to use an online speed test to find out what your maximum upload stream and maximum download stream is.  We suggest that you run this test using a fixed connection to the internet rather than using your wifi (wireless) connection to get the most accurate results.  It is also helpful to run this test during different times of the day so that you can see a good average of what you can expect from your internet connection.  

VoIP Speed Text Link

We recommend that you have you a high speed (broadband) connection to use VoIP.  A typical DSL connection will be rated at 600 kbps for the upload stream and 5000 kbps for the download stream. You will notice that your upload stream is almost always smaller than your download stream, which becomes your limiting factor for using VoIP service.

Your next step is to determine how many people in your office are likely going to be using the phone at the same time. For instance, having ten people on the phone simultaneously will require ten times as much bandwidth versus having only one person on the phone at any given time. Below is a chart that will help you calculate how many people can be on the phone at one time:

Full Quality Audio (G711 Codec	Compressed Audio (G729 Codec)
Uses 87 kbps for each concurrent phone call	Uses 33 kbps for each concurrent phone call
600 kbps ÷ 87 = 6 concurrent calls	600 kbps ÷ 33 = 18 concurrent calls

*based off of a typical DSL connection of 600 kbps upload/5000 kbps download

You will notice that we used the upload bandwidth in our calculation, as this is the limiting factor for VoIP calling. Keep in mind that you won’t want to push your connection to the limit as most cable and DSL con- nections do not have guarantees in terms of how much bandwidth they will deliver. If your internet connection drops in bandwidth at some point during the day, you don’t want your call quality to be affected. Other factors affecting VoIP are the latency of your connection and how much packet loss there is on it.

We typically do not recommend Asymmetric DSL for this type of service.

A router is the device that connects all of your computers and network equipment to your internet connection. It is an often overlooked piece of the puzzle that can have a major impact on the success or failure of your VoIP implementation. There are many routers on the market, some are very cheap (less than $40) and others can cost you thousands of dollars. We highly recommend that you avoid putting a poor quality or underpowered router in your office as it could cause an otherwise good VoIP installation to go bad.

Your router needs to be powerful enough to handle the number of phones you will have in your office and should also work flawlessly with VoIP equipment. A good place to start when deciding on your router is to speak with your VoIP service provider. We also recommend checking to make sure that your router is compatible with VoIP services. The following is a list of items which will help you determine whether or not your router is right for VoIP capabilities:

1. How many VoIP phones will you be connecting to the router? The more phones you will be connecting, the more powerful the router needs to be.
2. Will your VoIP phones have their own dedicated internet connection? If so, great! We’ll go into more detail on this later. If not, consider a router with Quality of Service (QoS) settings. This will allow prioritization of voice traffic over regular traffic and will help you avoid poor quality telephone calls. Again, we will go into further detail of this in the next section.
3. What other functions will the router need to perform? You might need your router to handle VPN connections, allow for wifi (wireless) connections, or perform other tasks.
4. Can you bridge your router to your modem? We recommend this as routers that are not bridged can cause installation related problems.
5. Never use more than one router or NAT gateway on the network at a time as this will cause problems for IP Telephones when they attempt to do NAT.
6. Does your router or firewall have any type of SIP settings, ALG, etc? If so, please disable them.

Call quality is a function of your network and the public internet. Some delays and network congesting cannot be avoided due to information traveling over the public internet while other types can be avoided. Good network design is critical to a stable and reliable VoIP implementation.

QoS refers to the ability for your router to prioritize VoIP traffic differently than regular internet traffic on your network, as well as the separation of VoIP traffic. VoIP is a real-time protocol, which means that if information is lost or delayed, it will result in a noticeable drop in call quality, and in some cases, just a complete loss of

it in general. Symptoms of network congestion include garbled audio, dropped calls, and echo. When setting up VoIP in your office, there are three possible ways to handle voice traffic. QoS is sometimes less crucial for a very small office (1-2 employees) but as the number of users and number of simultaneous calls goes up, the need for QoS does as well. The method you decide on largely depends on how much bandwidth you have, what you are using your internet connection for besides VoIP calling, and the level of call quality desired.

Below are the three methods, in detail:

1. No QoS – In this scenario, all voice traffic and regular internet traffic in your office are sharing the same internet connection. Because there is not QoS, there is no prioritization of voice traffic over regular traffic being performed; therefore, there is the high potential that voice quality could be degraded if there is insufficient bandwidth for both voice and regular traffic. Some customers will experience very few problems with this method, while others may report a high frequency of poor quality calls, dropped calls, and garbled voices. Again, this is entirely dependent upon how much network congestion your office has. This is not typically a method we recommend.
2. Router enabled QoS – In this scenario, all voice traffic and regular internet traffic in your office are sharing the same internet connection, but because your router is able to distinguish between these two types of traffic, it is able to give the voice traffic higher priority. This is absolutely a more preferable solution as it reduces the chances of poor call quality, dropped calls, and garbled voices. The only catch here is that most QoS enabled routers can only prioritize upload bandwidth, meaning that if your office has a high need for constant downloading, you may experience some of the same issues as if you were to have no QoS implemented at all.
3. Separated Traffic – In this scenario, all voice traffic and regular internet traffic are separated. This may take the form of implementing separate VLANs on the same physical network for voice and data to a fully diverse phyiscal LAN for voic eand data with separate connections for each (or, a separate prive connection for voice). This is the most preferable of methods, especially for larger offices with 5 or more employees and a high volume of uploading, downloading and calling. In this case, no prioritization is required by your router, because both types of traffic have its own dedicated internet connection. This is the absolute best way to ensure clear voice communications and the method we generally recommend whenever possible.