Wireless IP telephony enables phone calls using over a wireless network. It is a perfect solution for hospitals, warehouses and big campuses.
Wireless IP telephony
The same as VoIP – Voice over IP, VoWLAN reduces costs. It is done in a following way:
- Local calls are using a local WiFi network.
- External calls are routed over the Internet.
In this way you the cost of mobile telephony can be reduced significantly.
Terminals used for VoWLAN
Devices for VoWLAN could be all kinds of terminals as long as they have WiFi connectivity. This includes:
- cell phones
- dedicated VoWLAN phones.
Dedicated VoWLAN Phones
For dedicated VoWLAN phones I would recommend two options. The first is better and more expansive, while the second is optimal and cheaper.
- Cisco 7925G
- UniData WPU-7800
Cisco 7925G Unified WiFi VoIP Phone
Cisco 7925G is great solution for rigorous workspaces like warehouses, but also for normal office environments. It has the following features:
- Integrates communication with the voice, video and data.
- Bluetooth v2.0 headset which gives more freedom.
- Hermetically sealed phone and display which protects the phone from dust and liquids.
- Design compliant with the military standards.
- Rubber casing to protect the phone from damage caused by drops and shocks.
UniData WPU-7800 Wi-Fi VoIP Phone
UniData WPU-7800 is WiFi phone which has the following features:
- Advanced security standards – WPA2 personal and enterprise, 802.1xWEP, UMA.
- Automatic roaming – Mobility layer2/layer3 hands over.
- Enhanced power save technology – for longer life of battery.
- VMM – high quality voice
- Data, video and voice convergence.
- Auto provisioning.
Types of VoWLAN
There are two types of Wireless IP telephony:
- combination with cellular network
- local network which is independent from cellular network.
Benefits of the Wireless IP telephony
The biggest benefits of the VoWLAN are:
- mobility and flexibility
- improved productivity
- cost reduction
- using the features you want
- expansion of VoWLAN network at your own pace.
The Possible Problems of VoWLAN
The WiFi signal could have several potential problems.
- Interference with other wireless signals.
- Obstacles especially the one made of metal.
- Latency and jitter – degrades the voice quality.
- Low capacity reduces number of simultaneous calls.
- Problems with coverage.
- Roaming latency.
- Security problems.
- Dropping of packets and retransmissions.
- Power consumptions of terminals.
WLAN is a great platform for the IP telephony. To be effective and VoWLAN must fulfill the following needs.
- Signal strength which enables enough speed for quality voice calls.
- Minimal latency and jitter.
- Complete coverage.
- Seamless mobility.
- Users need to be close to the access point.
- This reduces power consumption of the user terminals.
- Increases data rates of WiFi signal.
The Requirements for Successful VoWLAN Implementation
The following requirements are needed for successful implementation of VoWLAN:
- demanding network architecture
- RF and site survey requirements
- carefully prepared Security
- WLAN roaming
- wireless quality of service – QoS.
More about the RF requirements you can find out in Radio Frequency Requirements (RF) for the Wireless Telephony
Read great document about proper design of WLAN network for Wireless IP telephony – VoWLAN Design Recommendations.
Voice over WLAN – The Final Remarks
VoWLAN technology allows different ways of communication to be totally integrated with enabling voice, data and video to be transferred over the same infrastructure or wireless network that uses WLAN standards. With proper hardware and software products you could optimize all these different features and functionalities, and provide interoperability between a wide range of applications. All five requirements (network architecture, RF site survey requirements, proper security, WiFi roaming and quality of service) need to be addressed to provide optimal functioning of this technology.