Voice over IP can deliver impressive savings on your phone service by enabling you to place calls over an IP network instead of using the traditional PSTN. It's also possible to run VoIP over wireless and cellular technology, with many cellular carriers offering hybrid handsets that can seamlessly switch to VoIP over Wi-Fi when a wireless network is in range - even while a call is active. By installing applications like Skype for Mobile, these devices can bypass the cellular network to make low-cost calls over the Internet from your home, office, or free public Wi-Fi hotspots
Landlines are becoming increasingly obsolete as these dual-mode phones deliver a single free-roaming solution, operating via Wi-Fi when available, and using the cellular network when out of range. However as with most integrated technologies, there are various pitfalls to consider, in addition to the obvious benefits.
These are the three major issues you might encounter with wireless and cellular VoIP calls:
- Voice transmissions are much more sensitive than data
Because voice is a real-time application, it is highly sensitive to the delay, jitter or packet loss that can arise from a weak signal or interference from nearby devices using the same frequency. If you have a bad cell connection, then your softphone will suffer too. If your wireless or cellular network is unreliable, then your voice over IP calls may experience unacceptable audio quality, dropped calls or even an absence of dial tone.
- Combining voice with data can impact audio quality
Due to the sensitivity of voice, any data transmissions that use the same connection will compete with voice packets, resulting in degradation of the audio quality. Users are generally willing to tolerate some delay on data networks, but when it comes to voice communications the service is expected to work reliably every time. It's essential to implement Quality of Service (QoS) to ensure voice packets are given priority.
- Voice security is a greater risk over Wi-Fi
Transmitting phone calls over the Internet already presents a higher security threat than using the closed PSTN service. And wireless exacerbates these concerns, since the signal must travel across the airwaves, where it could potentially be intercepted, rather than through physical cables. Your Wi-Fi network needs to be secure, with all traffic protected by encryption and authentication protocols.
So now you know about the issues, what can you do to avoid them? Unfortunately with the cellular network there's little you can do to improve the service, however wireless networks do offer some degree of control and configuration.
These are three steps you can take to ensure your Wi-Fi network is ready for Voice over IP:
- Conduct a wireless survey
Whether you're experiencing issues with your existing setup, or you're planning a new environment, a wireless survey is a useful way to optimise your Wi-Fi placement and identify potential blackspots. Tools like Ekahau provide highly detailed information to help you deploy your wireless network correctly. Note that a survey of a large site may take several days.
- Invest in wireless management tools
Many vendors offer network management tools that let you tune your network, produce a 'heat maps' of your wireless coverage, locate regions of heavy congestion, and identify rogue devices that may be transmitting in your vicinity. Addressing these issues can improve network performance and deliver better call quality.
- Reserve a channel for VoIP
This is an effective way to guarantee acceptable VoIP over Wi-Fi performance. You can select a specific frequency and channel to be used only for voice traffic, allowing data traffic to remain on a separate channel. This will ensure the data traffic never causes congestion of the voice bandwidth.