Designing a Wireless VoIP System

In my last post I discussed the benefits of utilizing wireless VoIP in both a WiFi environment and a cordless DECT environment.

Both types provide users the freedom of mobility while still being able to have constant access to their telephone.  Now we will look at how to go about designing and setting up a wireless VoIP system.   Since the cordless DECT phones have a base station that is directly connected to the network with CAT5 cabling, this post will focus on setting up a wireless network for WiFi phones.

Wireless LAN

In order to use wireless VoIP in your home or business, you must have a wireless LAN (local area network) set up so the WiFi phones can get internet connection.   The WiFi VoIP phones can use the same LAN that is also used for computers and other wireless devices.  To effectively make and receive VoIP calls the first necessity is to have a broadband internet connection with adequate bandwidth.

Routers and Access Points

Secondly, you must have a wireless broadband router, or a wireless access point connected to a broadband modem, in order to transmit the signal to the WiFi phone.  A wireless access point (WAP or AP) is a device that “connects” wireless communication devices together to create a wireless network.  The size of the area that needs to be included in the network, as well as the number of users, will determine how many wireless access points are required.   Placement of the access points is critical as well.  The obvious goal is to maximize the AP’s wireless range.

A usual range is a maximum of 300 feet, but walls and other environmental factors can produce interference that will decrease that range.  A distance of about 150 feet between AP’s is a safe number in order to have continuous coverage throughout the area.

Doing a site survey and strategically placing the AP’s throughout the entire area included in the network is encouraged as well.

Quality of Service

Another important factor to consider when setting up a wireless VoIP network is QoS, or Quality of Service.  QoS is the differentiation between types of traffic on a network so they can be treated differently and prioritized.  In a network where VoIP is used for communication, you will want to give the ultimate priority to the voice traffic over the data traffic.

This will help to alleviate some of the issues experienced with VoIP, such as packet loss, latency, jitter and echo.  The use of WiFi phones can increase the likelihood of experiencing those voice quality issues if QoS is not taken into account, which makes it very important to integrate routers that have QoS capabilities when setting up your network.

Security

The last point to touch on in this post is security of your wireless network.  Wireless communications are transmitted through the air, which makes it easy for hackers to intercept information if the network is not secure.  There are many wireless specific security solutions that you can implement including a few basic options listed here:

• WEP Encryption: Short for Wired Equivalent Privacy, WEP is designed to provide the same level of security as that of a wired LAN. (Note WAP is certainly stronger for encryption, but cross vendor interoperability is a hurdle. You should consider your circumstances before using WEP or WAP.)
• Change the default SSID (service set identifier) of the AP: most manufacturers have simple names as the default SSID’s and by changing it to something unique you can cut down on the opportunity for someone to hack into the network.  Disabling the SSID broadcast out to the wireless devices can help in this regard as well.
• MAC address filtering: Mac filtering is the process of configuring an AP with a list of MAC addresses that will be allowed or not allowed to gain access to the rest of the network via that wireless AP.  Only MAC addresses that have been registered with the AP are able to gain access to your network.

While wireless VoIP still has a long way to go in gaining the widespread acceptance of traditional cordless telephony, it is increasing in popularity every day as the technology is continually being developed and improved.  If you are considering a move to wireless VoIP and need assistance in selecting products or setting up your network please contact me at VoIP Supply at anytime.  I can be reached at 1-800-398-8647 x3873 or jshanahan@voipsupply.com.