Wireless telephony in business: WiFi matures

Wireless telephony in business: WiFi matures

Since the advent of IP telephony, the wireless seemed to go through wifi.It was without counting on the resistance of the DECT standard, which still displays undeniable advantages while managing to adapt to the IP world.Telephony on WiFi is however in the process of filling its shortcomings, which concern both the infrastructure and the handsets.

802.11R and the Enterprise Voice label put order

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In terms of infrastructure, the passage of the voice requires special management of the quality of service, implemented in terms of terminals and wifi controllers.This component has been treated since 2003 thanks to the 802 standard.11th, which gives priority to the voice and reserve it from the bandwidth.But it does not cover the management of dynamic terminal change, which generates a significant period.To make this latency compatible with a conversation, Spectralink (whose offer is sold in OEM to large PBX manufacturers) and Cisco have developed their own mechanisms in order to ensure an imperceptible tilting - we speak of "fast roaming".

Very recently, another variant of WiFi called 802.11R came to put good order."Its implementation will be rapid because it requires only a change of firmware," announces Vincent Blavet, network consultant for WiFi technologies at Cisco.At the same time, the Wi-Fi Alliance consortium, which oversees the certification of products, will define a label called Enterprise Voice, which will include interoperability tests with 802.11th and 802.11R.

WiFi evolves to comply with application flows

Téléphonie sans fil en entreprise : le WiFi arrive à maturité

Another evolution concerns the support of the different versions of WiFi.The standards usually used in Europe are 802.11b and 802.11g, both operating on the frequency band of 2.4 GHz.Now supported by certain terminals targeting companies, 802.11a, which operates the 5 GHz band, helps avoid disturbing application flows."We do not advise to dedicate this band to the voice, but in practice, the handsets will naturally connect to the least congested band," says Vincent Blavet.

However, it will rarely be possible to save an upgrade of an existing WiFi network, previously dedicated to data."In order to reduce the consumption of handsets, we advise to pass the emission power to 30 milliwatts (MW) instead of 100 milliwatts, which can lead to increasing the density of terminals," said Mathieu Gagnaire, pre-sales engineerAt Telindus.

Telephone combination: still incomplete compatibility

It is still necessary that telephone combins offer a sufficient choice, support all the mechanisms managed by the terminals and display good autonomy.The choice widens slowly, at least in the range of professional products.Among those entirely dedicated to WiFi, suppliers are practically reduced to ASCOM, Spectralink and Cisco.The latter has just replaced its 7920 model with the 7921, which supports 802.11a and offers a nine -hour autonomy in conversation and forty hours in standby, twice better than the 7920, at a cost of around € 350.DECT handsets are always better for much cheaper, but cannot behave in intranet terminal.

We also see emerging Bimodes, WiFi and GSM handsets, especially at Nokia, with the E60.Alcatel and Cisco dedicate them to customer software which provides support for the functionality of their IP-PBX.This model does not recognize 802.11a, but it is compatible with the quality of service and fast roaming mechanisms of WiFi terminal manufacturers.Cisco has also just signed an agreement with RIM so that its future blackberry benefit from comparable integration.

In theory, Windows Mobile or Symbian smartphones become bimodes for the installation of a soft phone, or Skype VoIP software."But in WiFi communication, they are currently showing ridiculous autonomy, even in standby, because they do not exploit any material saving mechanism of battery," regrets Mathieu Gagnaire.

DECT/IP terminals in terms of DECT equipment

Faced with WiFi, dect gradually loses its advantages.For two years, manufacturers like Aastra, Mitel, Siemens and Avaya have released so -called DECT/IP terminals.Directly connected to the IP network, they interface between an IP-PBX and DECT phones.At Aastra Matra, we still defend beak and nails this approach.“In less than two years of marketing, our sales of DECT/IP terminals have reached the level of our traditional dect equipment.At the same time, we have not noticed a take -off of telephony on WiFi, "says Dominique Poizat, Marketing Director produced at Aastra, while admitting that things are in full.

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