How network affects VoIP

How important is your network to the quality of your VoIP service?  The question is better stated, “How important is the quality of your voice?”  In the VoIP paradigm, a number of factors affect voice quality and uptime: platform, quality of service from your service provider, your LAN, and also your network. In the “old days,” PRI or POTS services from any telephone company were ubiquitous commodities and relatively easy to get right.  With the pending death of the PSTN, choices of network for VoIP will become much more critical to ensuring high quality services.

Types of network for VoIP

The main types of network for VoIP in today’s market are 1) Broadband (BYOB) 2) Dedicated internet access (DIA), and 3) Multi-protocol label switching (MPLS).  Many customers ask me for recommendations for their network for VoIP.  Here are several considerations: 

1. Make sure you have the appropriate bandwidth for your voice calls. 

There are 2 commonly used compression techniques for VoIP that take up either 30kb/s or 80kb/s per call.  A good rule of thumb for a non-call center business is that 25 – 50% of your total number of phones will be the maximum capacity you’ll have on the phone at any given time.

You’ll know you are under-trunked if you get busy signal complaints from customers or your employees.  If you feel you might be over-trunked, call your phone company and ask for a utilization report.

2. Determine if cost is really more important than quality and uptime.

Just about every business owner knows that the cable companies offer better bandwidth than traditional telecom circuits.  An example of this is that Comcast has become one of the largest telecommunications companies in the country over the past 10 years.  If you want to save some dollars, you can use voice and data services over a single cable connection.  Broadband is a reasonable network for VoIP for small businesses.

However, if cable service is spotty or you consider voice or other applications in your business to be critical, you should consider a dedicated connection with guaranteed speeds and an SLA.  The best way to do this is to get a dedicated connection for voice and other critical applications, and use the cable connection for Internet surfing and backup.  Not only will you get better service for your critical applications, but you’ll also be able to use the cable for more bandwidth-intensive usage, and you will have a failover option if either circuit fails.


This architecture uses a dedicated, prioritized circuit for voice and data, and the BYOB cable circuit as backup only.


This architecture uses a dedicated, prioritized circuit for voice while data travels over the BYOB connection. Both circuits back each other up for voice/data.

3. Determine if you want your circuit to be public or private.  

By utilizing MPLS, you can keep all of your critical traffic, including voice, completely invisible to the outside world.  This takes VoIP to another level of security that was unmatched by PSTN calling.  Many business owners and CIOs have doubts about VoIP that traverses the public Internet for security reasons.

Companies like Masergy can offer guaranteed in-sequence packet delivery over a “public” Internet circuit, thus guaranteeing voice quality.  And despite the use of the word “public,” this is still more secure than a traditional PSTN call.  It is remarkably easy to tap into a traditional phone call using analog equipment.  It is much more difficult to hack into an IP call, but if your business demands the highest level of security, you’ll want to route that traffic over a private MPLS network.

4. Ask your provider what options they offer for network for VoIP.

In my telecommunications career, I’ve learned a great deal about network sophistication and the importance it plays in critical applications, voice being an extremely important one of them.  I’ve known for years about the role of QOS and MOS on the LAN side of things.  Many carriers don’t even offer those features.  But more importantly, none of those quality controls mean anything if the WAN that those features ride on isn’t groomed for voice.

Just like any chain, the service is only as strong as its weakest link.  Businesses that seek higher quality VoIP services will also need to seek a high quality network for VoIP.  And here’s a little secret you might not be aware of: High quality circuits can cost the same or less than the ones with poor quality.