Fixed-Mobile Convergence
Is UMA right for enterprise FMC?
Carrier-based wireless coverage
requires no equipment at customer premises.
by Steve Shaw and Peter Thornycroft
Enterprises
have several different options for
fixed-mobile convergence (FMC)
architectures, depending on how closely the
mobile phone is linked to the enterprise
PBX, where the phone number is hosted, and
what voice and data calling features are
offered on the phone. IT professionals
should consider business benefits and
challenges when evaluating these options and
determining which architecture is the right
choice.
In PBX-centric architectures, all
incoming calls are directed to and all
outgoing calls originated from the PBX
number. When a cell phone, equipped with a
PBX-specific software client, is in range of
the corporate Wi-Fi, voice-over-IP (VoIP)
protocols connect it directly to the PBX.
Even when the cell phone is outside Wi-Fi
coverage, it continues to act as a PBX
client.
PBX-independent architectures are based
on third-party adjunct servers that work
with different types of IP PBXes and require
special client software on the handset,
primarily for Wi-Fi connection and
handovers. The server is an anchor point for
call handover, but usually relies on the PBX
and its telephony gateways to dial outside
calls.
Carrier-centric architectures follow a
different path to FMC; they connect mobile
phones to Wi-Fi networks, and the phones
receive all services from the mobile
operator. These architectures require no
equipment at customer premises and no
integration with the IP PBX.
Since many cell phone customers already
use their phones for most of their business
communications, they are not closely tied to
the corporate PBX. Thus, many enterprises do
not require an FMC architecture that
incorporates the PBX. Instead, looking to
capitalize on the high bandwidth and
extensive indoor coverage of existing
enterprise Wi-Fi networks, mobile operators
are leveraging the 3GPP unlicensed mobile
access (UMA) standard to provide a solution
that meets the needs of the end-user.
Because UMA is a standard, all major mobile
handset vendors now offer UMA-enabled
phones.
The UMA-based approach is simple to
adopt, requires no new user behavior and
offers a single-number solution.
Essentially, UMA turns Wi-Fi networks into
seamless extensions of the wireless
carrier’s outdoor cellular network.
Gaining or improving coverage in areas
where cellular signals are weak is an
important issue for some organizations. UMA
extends coverage to the workplace without
forcing employees to change the way they use
their cell phones. The only difference is
that the phone will switch to Wi-Fi when it
loses cellular coverage. The use of UMA,
however, does not rule out the use of
unified communications (UC); in fact,
enterprises can combine FMC and UC to
provide advanced, time-saving
features–indoors and outdoors–to their cell
phone users.
To improve coverage with UMA, an
organization sets up Wi-Fi access points in
areas with poor cellular coverage to
overcome coverage gaps and call dropouts.
Companies with state-of-the-art, centrally
managed wireless LANs (WLAN) can make a
global configuration change to enable Wi-Fi
UMA access from any location.
When organizations designate budgets to
add PBX numbers and subscriber licenses to
all field-based employees who have never
before had a PBX extension, using UMA in
conjunction with the employees’ home access
points is an alternative approach to
enterprise FMC, offering users improved
mobile coverage at lower costs. There is no
single FMC solution for all situations,
however, and maybe not even a single
solution per organization.
UMA also can save money by providing a
higher degree of IT control over
reimbursements for employees’ cell phone
costs, particularly on international calling
or roaming. The enterprise can also benefit
from the reduced operator expenses enabled
by UMA, since it enables operators to
offload cellular calls to Wi-Fi and take
advantage of favorable tariffs to offer
users improved coverage and data
performance.
How much money enterprises will save
depends on the UMA carrier’s tariffs, the
cost of alternative communications methods
that might be used and the calling patterns
of corporate users. As employees
increasingly use their mobile phones to make
calls over Wi-Fi, the minutes used on the
fixed network, in effect, decrease.
PBX trunks are billed by the fixed-line
carrier, whereas cellular plans include
nationwide long distance and result in
additional savings to the employee and the
enterprise. Telecommuters and remote
employees may save even more, as they may no
longer require a fixed-line voice service, a
broadband connection and mobile service to
meet all their communications needs.
UMA may also enable enterprises to save
costs on international roaming. While a U.S.
user may not save any money when calling
France, for example, some operators’ plans
allow U.S. users traveling in France and
using Wi-Fi to call the United States
without incurring any calling charges. Plus,
incoming calls when in France may not incur
international roaming charges if the user is
within Wi-Fi coverage. Since international
cellular roaming charges are often
significant, UMA has the potential to
provide substantial savings.
Finally, some UMA phones can bypass the
UMA tunnel over Wi-Fi for non-operator
services such as Internet browsing. This
will not only improve performance but also
save costs, since the data will not be
metered by the carrier. Using a UMA phone,
when it is operating within Wi-Fi range, for
data services such as e-mail and Web access
also leads to cost savings.
Steve Shaw is vice president of
market development at
Kineto Wireless, Milpitas, Calif.
Peter Thornycroft is director of product
marketing for
Aruba Networks, Sunnyvale, Calif.
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