As VoIP is run over a broadband connection, before you consider adding VoIP onto your CRM account we recommend that you read the following document so that you understand the requirements in terms of broadband speed, suitable routers and interpreting the results of both a speed test and a ping test. 


VoIP - System Requirements, Routers and Speed Tests


Switching from a traditional telephone service to voice-over-IP (VoIP) requires sufficient bandwidth (speed), a proper switch and router, and a good battery backup solution to protect you from power failures. 


A number of factors must be considered when setting up VoIP including how many users you will have on a single internet connection and how many of those users will be on the phone at once. 


Bandwidth - Determining how much bandwidth you will need for voice-over-IP in your office is your first step.


The Router - Choosing a low quality or under-performing router is a costly mistake which will degrade your call quality - please click here to view some information on compatible and incompatible routers for VoIP. 


Quality of Service - QoS - You must decide whether voice traffic will be separated from regular internet users or if it will share the same network.


VoIP Equipment –We also supply a range of VoIP phones and equipment which is fully compatible with our CRM.

To view the range of VoIP cordless phones and headsets available please click here

To view the range of VoIP corded desk phones and headsets available please click here.


Power Failures - Voice over IP does not work when the power goes out so you should install a battery backup system and possibly a Power-over-Ethernet switch if your budget permits it.


Available Bandwidth 


The first item examined during the VoIP speed test is bandwidth. Bandwidth measures how much data your internet connection can send (upload) and receive (download) over a time period of one second. 


In most cases your upload bandwidth and download bandwidth will differ considerably. 


Upload bandwidth is the limiting factor when determining whether you have enough bandwidth to sustain a certain number of concurrent telephone calls using VoIP.

As an example, a typical voice call requires 87 Kbps of upload and download bandwidth. Did your VoIP speed test indicate that you might not have enough bandwidth for your desired number of users?


How much bandwidth do I need? 


Voice over IP needs 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 download stream is. We suggest you do this test using a fixed connection to the internet rather than using your wifi (wireless) connection to get accurate results.


Try to use numerous tests during different times of the day to get a good average of what you can expect from your internet connection. Bandwidth is normally measured in kbps or kilobits per second. 


You will need to have a high speed (broadband) connection to use voice-over-IP.  


A typical DSL connection will be rated at 600 kbps for the upload stream and 5000 kbps on 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 a 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 will require ten times as much bandwidth as having one person on the phone. 


Below is a chart which will help you calculate how many people can be on the phone at one time: 


Ask your voice-over-IP service provider what audio codecs they offer as there is a trade-off between audio quality and bandwidth usage:


  • Full Quality Audio (G711 Codec) - Uses 87 kbps for each concurrent phone call (NEB) 
  • Compressed Audio (G729 Codec) - Uses 33 kbps for each concurrent phone call (NEB) 


So the calculation for a typical DSL connection would be: 


DSL connection: 600 kbps upload / 5000 kbps download 


Gives us (Full Quality): 600 kbps / 87 kbps = 6 concurrent calls 


Gives us (Compressed Quality): 600 kbps / 33 kbps = 18 concurrent calls 


Notice we used the upload bandwidth in our calculation as this is the limiting factor for voice-over-IP. 


You also do not want to push your connection to the limit as most cable and DSL connections 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 do not want your call quality to be affected. 


Other factors affecting voice-over-IP are the latency (ping) of your connection and how much packet loss there is on it.


The VoIP speed test considers a wide range of factors that determine your connections suitability to VoIP; please read the results carefully.


What can I do to get even faster upload speeds and bandwidth with my current broadband ADSL package?


If you are unable to access Fibre Optic Broadband i.e. BT infinity in your area and can only get ADSL broadband then speak to your current or new Internet provider to see if they can provide your business with Annex M bolt-on.


What is Annex M?


Annex M is the latest generation of broadband technology that allows for greater upload speeds as a bolt-on to ADSL broadband. 


Annex M can potentially increase upload speed to 2.5 Mb, and is available as an enhancement for those customers who could benefit from faster uploading, including remote workers, heavy email users and those who need to regularly upload large files.


Can it improve VoIP bandwidth and speed?


Other reasons that businesses choose to upgrade to an Annex M connection include more effective video conferencing, more bandwidth for voice over internet protocol (VoIP) calls, and sending offsite backup information faster.


When using VoIP as well as running your CRM your business would benefit from an upgraded ADSL package that includes Annex M.


Choosing a Router - Factors to Consider: 

A router is the device that connects all 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 voice-over-IP implementation. 


There are many routers on the market, some are very cheap and others can cost you thousands of pounds. 


There is nothing worse than putting a poor quality or under-powered router in your office which 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 voice-over-IP equipment.   


We also recommend checking to make sure that your router is compatible with voice-over-IP services, such as being able to disable the SIP ALG setting and enable DHCP on your router is essential for good quality VoIP. 

If you will be prioritising voice data over Internet usage, your users could notice a significant slowdown in internet usage if your router cannot sufficiently handle your data demands. 

1. Quality of Service (QoS)

Before you get a VoIP service, the most critical feature for a VoIP router is quality of service (QoS). This ensures your hardware is prepared to prioritise voice traffic over other data transmissions, including Internet usage and streaming. 

Without QoS, you could run the risk of equal prioritisation. If your bandwidth usage peaks, you could run the risk of dropped calls or noticeable decreases in call sound quality.

For most businesses, phone communications are a critical tool for customer communications. As a result, VoIP QoS prioritization is a must-have for any router.  Please click here to see more about QoS.

2. Compatibility of Router for VoIP 

Some routers are incompatible for using with a VoIP Service as settings can not be changed to allow for VoIP traffic which can cause issues such as calls dropping out, calls cutting off and impact on call quality. 

3. Ports

Data is sent to your router via your IP address, which is designated according to protocols or applications. Ensure that your VoIP application assigns data to ports automatically, or you could risk a drop in QoS. While there are workarounds to create port forwarding, port assignment according to need is most efficient.

4. Consider Dual-Bandwidth

For organisations with a high demand for data transmission, purchasing two routers and planning for dual-bandwidth can be a way to maintain high-service quality. 

Depending on your needs and requirements, you could decide to optimise one wireless connection for Internet usage and another for voice communications. While this approach is not necessary for most organisations, it can simplify managing high user demands for data transmission.

The following is a list items which will help you to determine whether your router is right for voice-over-IP: 

1. How many voice-over-IP phones will you be connecting to the router? The more phones you will be connecting, the more powerful the router needs to be.  Do not use a cheap router to run an office with 10 IP Telephones.


2. Will your voice-over-IP phones have their own dedicated Internet connection?  If not, a router with a quality of service (QoS) setting to prioritise voice traffic over regular traffic is an absolute must.  Without QoS you will encounter poor quality telephone calls regularly.


3. What other functions will the router need to perform? You might need your router to handle VPN connections, allow wifi (wireless) connections or perform other tasks.


4. Make sure you can bridge your router to your modem. Routers that are not bridged can cause problems with voice-over-IP installations.


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. Is your router on a fixed or dynamic IP address?  If using a fixed IP address we will need to configure your VoIP phone equipment specifically for this so it is important you let our Support Helpdesk know. 

We recommend the following routers for compatibility with VoIP:

  • Asus DSL AC55U
  • Technicolor TG582n PRO or the TG589n
  • Cisco RV042(G) / RV082 / RV016 / RV110W / RV180W / RV320
  • Cisco Integrated Services Routers (1900/2900/3900 series)
  • Draytek 2830 / 2820 series
  • ZyXEL range
  • Linksys by Cisco ADSL and cable routers


Please note: there are some known issues with using a Virgin Hub for VoIP as many have found they are unable to make outgoing calls with a Virgin Hub.  If this happens you can purchase a new router and put the Virgin router into ‘bridge’ mode. 

Battery backup and Power-over-Ethernet


With voice-over-IP and most office telephone systems you must consider what happens when the power goes out. For some offices this can be a regular occurrence and for others it might happen with a very low frequency. Once of the things you will need to decide is whether or not you will install a battery backup system.


Here are a few important terms you should know: 


  • Power over Ethernet (PoE) - is a technology that allows VoIP over IP telephones to be powered using regular network cables rather than power adapters which plug into the wall. This has the advantage that you can power all the phones in your office from a single source and makes installing a battery backup unit much easier.  You can purchase a PoE kit at:


The easiest way to protect your phone system from a power outage is to power all the phones using a Power-over-Ethernet (PoE) switch that would normally be connected in the back room where your router and cable/DSL modem is located. This has the advantage that all your phones are drawing power from a single source which you can backup using an uninterruptible power supply (UPS). 


All you need to do is plug in your PoE switch, router, and DSL/cable modem into a sufficiently powerful UPS device so that when the power goes out all your phones remain up and running. 


Speed Tests 


For VoIP, enough bandwidth must be supplied to allow for the transmission of voice data in real time.  


In order to establish the quality of your broadband to support a VoIP line we ask that you carry out a speed test. This test is done online via 


The VoIP speed test below will test ping (latency), download speed and upload speed results that you can use to evaluate your broadband connection.  


Download speed: When you connect to the internet, the download speed is the pace at which data (websites, programmes, music etc) is transferred from another source to your device. For VoIP the higher the download speed the better for call quality. 


A slow internet download speed can become very annoying if your downloads take forever and the video clip you are trying to watch keeps stalling. As a general rule, if you are going to rely on downloading a lot of content, or play a lot of online games, it is definitely worth looking at getting the fastest connection you can comfortably budget for.


Upload Speed: this is the speed at which data is uploaded to the internet – such as posting on social networking site such as Facebook, or to upload images to a company website.  


 The higher the upload speed the better – for instance 10mbps (megabytes per second) is a very good score.  Essentially, the upload is going in the opposite direction to the download - from your computer to someone else.


Broadband upload speeds are generally much slower than download speeds. The reason for this is that people generally do far more downloading than uploading, so downloading is given priority by the ISPs.


Upload speeds are more important to people who are going to be doing large amounts of uploading, such as someone who works from home and wants to exchange files with a remote network, or people who play a lot of online games - especially if they are hosting them themselves.


Again, distance from your telephone exchange, as well as other considerations such as old household wiring, can also be factors in slowing down your upload speed.   As a minimum we can accept 1 or 2 Mbps for upload speed.


Ping (latency): This measurement tells how long it takes a "packet" of data to travel from your computer to a server on the Internet and back.  Whenever you experience delayed responses in Internet applications - this would be due to a higher than desired ping.  Similar to packet loss, lower is better when it comes to ping which is measured in milliseconds.

A result below 100 ms should be expected from any decent broadband connection.


The Ping test will show you the:


Line Quality: (MOS score) should be higher than 4.0 normally you will get a rating i.e. A or B – this helps to show good quality – A being the best – see below for more info:


Mean Opinion Score (MOS):


Rather than judging the quality of a voice connection by subjective terms such as "very bad" or "great," the voice industry has developed a scoring method to quantitatively measure what level of voice conversation you can expect. 


This is called the Mean Opinion Score or MOS. The MOS gives us an indication of the perceived voice quality of the media after you have received it. 


MOS is expressed in the VoIP speed test as a number ranging from 1 to 5, where 1 is the worst and 5 is the best. The values do not need to be whole numbers. 


MOS Ratings Table : 


5ExcellentExcellent sound quality (virtually perfect)
4GoodGood sound quality resulting in a call similar to a long distance phone call.
3FairPhone conversation has some interruptions requiring parties to repeat what was said
2PoorEach party has issues hearing the other one speak clearly
1TeribleNeither party can communicate effectively

An MOS score that drops below 3.5 is considered poor quality, a measure of 4.2 - 4.5 is considered good quality.

Jitter: This is one of the most important factors examined during the VoIP speed test. In basic terms, jitter is the difference between when packets are expected to arrive and when they actually arrive. 


This often has little impact when you are browsing the web or downloading an e-mail, but for a real-time application like VoIP it makes a big difference. In the world of VoIP, timing is everything, and when the timing of packets are constantly being received at unexpected times, an unstable voice connection can result. 


Watch carefully for this during the VoIP speed test – the lower the score the better such as for instance 2ms (milliseconds) is better than 4ms.


A high level of jitter will cause severe degradation in call quality. If you saw a high level of jitter after running the VoIP speed test, you should be aware that your connection may have problems that could prevent it from properly running a VoIP service. 


Packet Loss: Packet loss refers to how much information is being lost during transmission; it is expressed in the VoIP speed test results as a percentage. For instance, packet loss of 5% means that 5 per cent of all data transmitted is not reaching its destination. 


The lower the percentage rate the better – with the best result being 0%.


Packet loss can be caused by failures in network cables within the office, excessive network congestion, or general problems with network switching equipment. 


Packet loss can be constant or occur in bursts. However, bursts are more typical of packet loss. A burst of packet loss over a period of a few seconds will result in little or no voice traffic reaching you and thus you may miss much of the conversation. 


The following results from a speed and ping test would be as follows:   

  • MOS score of 4.0 or higher
  • Upload speed is important (faster than 1mb)
  • Download speed will depend on their environment – if there are lots of people all sharing a small amount of bandwidth – then it can cause issues. We use high definition codec – which requires 80 kbps in each direction. 
  • Low latency is good
  • Jitter as low as possible, the lower the score the better.
  • Packet Loss – ideally 0% - if there is packet loss this has a significant impact on call quality


Generally speaking if you are on an ADSL / FTTC / Virgin broadband connection there should be no problems with adding a VoIP line.  

However please note that if you are on a satellite broadband connection then we do not recommend VoIP as it will not be sufficient to support good quality calls. 


Different Results at Different Times 


Why might you get different results from a VoIP speed test at different times? Networks are dynamic environments and conditions can change depending on network usage, time of day, and other factors. 


It is best to run the VoIP speed test a few times at different times of the day, or after you experience a network related problem, to try to determine the source of the issue. For instance, you might experience a voice drop-out when an employee is uploading a large file but not at other times. 


If you did not have Quality of Service (QoS) set up properly this would affect your voice conversation and thus it would only appear on a VoIP speed test if the employee was still uploading the file - once they had finished the upload, the test might indicate perfectly good results.