Mixed Signals. Vendors Differ on How to Tie SS7, IN with IP Telephony [Nice SRA references]
soundingboardmag.com
By Fred Dawson
Anybody in a hurry to begin putting intelligent
network (IN) capabilities into play over Internet
protocol (IP) telecommunications networks faces a
bewildering choice of approaches, any one of which
might turn out to be one of those legendary
bleeding-edge mistakes.
Service providers who are pushing vendors hardest
and the vendors who are responding most
aggressively are generating a stream of options at a
moment when the means by which IN and IP
systems talk to each other has not been standardized,
leaving it to the pioneering users of IN over IP to
guess whether their chosen solutions will endure.
Complicating things further is the search for
crossover solutions in which the legacy IN
infrastructure is leveraged to maximum advantage,
even though virtually everyone looking at making
packet voice a toll-quality service believes a purely
IP version of IN offering the same and many more
features but with a different architecture is the
ultimate goal.
"Part of what we need to evaluate is what makes the
most sense to replicate in the way of IN features
inside [the IP network] vs. providing the same
features on the life cycle of what's outside," says
Mike Gettles, lead engineer for advanced technology
development at Sprint Communications Co.
(www.sprint.com). "From our perspective, we need
carrier-quality service support for communications
within the IP network and for communications
moving in and out of the PSTN (public switched
telephone network)."
Where to draw the lines on IN is one of the key
questions Gettles and his colleagues have left to
answer as they resolve remaining design issues for
the first iteration of Sprint's Intelligent On-Demand
Network, slated to go into com-mercial operations
this fall. As Gettles notes, "There are plenty of
service capabilities that already exist in the PSTN
environment that are useful in a packet network, so
we have to be careful about reinventing the wheel."
Yet Sprint and other carriers small and large who are
making their local service play in the IP domain
believe the wheel will end up being reinvented
eventually, owing to the flexibility and scalability of
the emerging IP platform vs. the proprietary
switch-linked iterations of IN in the PSTN. This
perspective is the driving force behind the sudden
presence of computer companies such as Compaq
Computer Corp. (www.compaq.com),
MicrosoftCorp.(www.microsoft.com), Sun
Microsystems Inc. (www.sun.com), and others in the
IN-over-IP space who believe the new service
provisioning paradigm will shift IN applications
development away from traditional vendors to their
hardware and software platforms.
"What we came to realize and our customers realize
is that because their services are IP-based we could
migrate away from the switch-based SCP (service
control point) model and run the service on web
devices, whether it's the web server, a PBX (private
branch exchange) or handsets," says Paul
Tempest-Mitchell, manager of systems engineering
for Sun. "This opens development up to virtually
anyone with a PC."
Sun is using the object-based Java programming
language to develop a toolset it calls "JAIN," for Java
Advanced IN. But Sun's approach isn't a complete
divorce from traditional IN, insofar as it retains the
idea of working from SIBBs (service independent
building blocks), which are the object-based units of
feature development in IN.
"Java is an object-based language and so JAIN
makes an excellent tool for working within the IN
architecture," Tempest-Mitchell notes.
Switched-based incumbent carriers such as Sprint,
which has Class 5 tandem switches in place
nationwide (though it has stopped installing them),
can tap into IN working with those switches both to
deliver instructions through the IP side of the
network, once the messages are converted to IP, as
well as to give Sprint customer connections IN
support over the PSTN. Providers of IP telephony
who don't own switches don't have this luxury unless
they can gain access to a legacy carrier's IN base,
which, as Tempest-Mitchell suggests, isn't something
they can count on.
"Early on you won't see people enabling access to
their switches for unfriendly applets,"
Tempest-Mitchell says, in reference to the potential
of using Java-based software to extract IN
applications from switches. As a result, the JAIN
strategy requires that gateway servers and
gatekeepers be equipped with the overlays of JAIN
software that would populate a carrier's IP domain
with IN capabilities, he adds.
But Sun's solution to equipping the IP network with
IN is but one of many racing into the marketplace at
this point, all offering different ways to mimic and
exceed the capabilities of IN. As Allie Kafel, director
of telecommunications for Stratus Computer Inc.
(www.stratus.com), notes, these capabilities include
a lot of things beyond support for service features
such as 800 numbering, call forwarding, caller ID
and other Class 5-type services, including the means
developed by Stratus for preventing data over PSTN
lines from clogging switches.
This is the application that started Stratus, a
long-time supplier of middleware allowing computers
to work as IN adjuncts to switches in the PSTN
domain, down the road toward developing
IN-over-IP solutions more than a year ago, Kafel
notes (Sounding Board, May/June). The Stratus
approach employs the signaling system 7 (SS7)
hierarchy, which is used not only to provision service
features from the switch but to perform basic
trafficking functions such as setting up a circuit
connection at a remote switch, he says.
"Our box understands SS7, which allows it to take
the request for a circuit from the originating switch
and set up a direct connection to the remote access
server (RAS), bypassing the terminating switch,"
Kafel says. "The Stratus box knows all the states on
the RAS and so can tell the original switch what
trunk lines are available into the RAS, which allows
that connection to be made without using the local
switch."
This integration into the PSTN via SS7 and into the
RAS via TCP/IP puts the Stratus technology in a
solid position to evolve toward full support for IP
both within the IP domain and across the gateway,
Kafel says.
"One of the values we bring is that, through our
agreements with major RAS suppliers, we can offer
solutions that talk to multiple RAS's within a
provider's network, which is important in the absence
of any standard for linking between SS7 and IP."
Stratus is moving into what it sees as the second
phase of this evolution, with product development
now complete on software that will allow
pre-circuit-setup information using the TCAP
(transaction capability application protocol) in the IN
hierarchy to be applied in bypassing switches,
meaning that connections will be established through
interaction with multiple RASs at one time, thereby
extending routing flexibility for 800 numbers and
other applications.
Beyond this step comes the full implementation of IN
within the IP domain, which entails adding the
capabilities of an SCP to the IP telephony
gatekeeper, achieving the ability to operate
independently of as well as in cooperation with
external switch-based IN platforms.
Stratus is teamed with Ascend Communications Inc.
(www.ascend.com), Bay Networks Inc.
(www.bay.com), Cisco Systems Inc.
(www.cisco.com), 3Com Corp. (www.3com.com)
and other entities in efforts to standardize the
message set between the IP IN platform and RASs. [Fascinating what will happen...]
Standards are well and good, if you're content to
wait, but I-Link Inc. (www.ilink.net), the
next-generation IP communications company that has
built much of its networking intelligence on the
technologies supplied by its wholly owned
subsdiaries, MiBridge Inc. and ViaNet Technologies
Ltd., is not waiting.
"We're getting the SS7 core code from other
vendors, but we're implementing IN using our own
technology inside our gateways," says Bob Bryson,
vice president of product marketing for I-Link.
I-Link, now serving some 35,000 customers in 25
markets from a standing start of zero a little more
than a year ago, anticipates growing to 250,000
customers by the end of 1999 as it adds ever more
features and functionality to its service portfolio,
Bryson says.
"The industry is evolving in the direction we're going,
but we can't wait for vendors to mature products
under the standards process," he adds.
Building Blocks
With software initiatives underway to bring a wide
range of IN-like capabilities into play later this year
and next year, I-Link looks on H.323 as a "subset"
of the system it is putting in place, Bryson says.
"We're moving beyond the classic gateway
mentality," he says.
A case in point is the carrier's use of its backbone
network in conjunction with SS7 capabilities to give
customers a "1+" dial-in option as opposed to the
typical seven-digit-through-the-gateway dialup
access to discounted IP voice services. The SS7
signal over the dialup link to the customer ensures the
1+ dialer's call is sent through the local central office
switch and then routed to a gateway into I-Link's
backbone, where the caller can benefit from the
features and low costs I-Link offers, but at a
premium over the price paid by the seven-digit dialup
customer.
"Some people are more comfortable dialing in the
way they're used to, so we've made that an option to
help extend our market base," Bryson says, noting
the price difference comes to about 1.5 cents to 2
cents per minute over the 4.9-cent price I-Link
presently charges for calls via the seven-digit direct
gate-way access.
Even though much of the cost break over traditional
long distance goes away, I-Link is betting on its
ability to offer special features as its primary market
draw in going the 1+ route, Bryson notes.
"We think price is a starting point for us in building a
market base, but just the starting point," he says.
The current feature set, including integrated voice and
fax service, call "find-me," conferencing, enhanced
e-mail and a variety of custom calling options,
depends on IP-based functions built into the I-Link
backbone, offering customers lower cost alternatives
than are typically available from incumbent carriers
via IN-equipped circuit switches. In the company's
next big leap, the network functionality will be
extended to the customer premises via what Bryson
calls "C-4," a customer communications control
center device being developed by ViaNet for
deployment in the second half of next year in
conjunction with use of high-speed access lines.
"C-4 is an extension of the network to the premises,
where we'll be able to provision up to 16 lines as
well as Internet access over ISDN (integrated
services digital network) or ADSL (asynchronous
digital subscriber line), depending on what is
available in the market," Bryson says. "If we're going
to use ADSL, we want to be able to control the
ATM (asynchronous transfer mode) layer."
The C-4 box, with 10baseT connections to
computers as well as links to standard phones, puts
the IP gateway in the home or office, breaking away
from the H.323 gateway model in much the same
way that Sprint envisions for its ION. In both cases,
the computational power in the premises device
brings the network intelligence to the end users,
allowing users to configure their applications to suit
specific needs.
C-4, which goes into alpha testing in the fourth
quarter this year, will allow I-Link to use wider
bandwidth pipes to deliver such enhanced services as
videoconferencing, multimedia multicasting, virtual
Centrex and much else to end users, Bryson says. In
addition, he notes, the company has developed the
IN capabilities necessary to handle the billing and
administration required for the wide-ranging service
options in store with C-4.
Where Sprint is concerned, the attraction of the
endless featuring capabilities of a network element
extension into the premises must be weighed against
the cost advantages of distributing that intelligence
from shared access points in the network.
"In the type of data network we're building, you're
not confined by physically locating the intelligence at
a switch, but we're still in the process of determining
how to distribute it," Gettles says.
"The problem you have as you make the hub at the
customer premises more intelligent is that it requires
you to use a bigger processor with more memory
and storage space," he adds. "What I'm trying to do
is make the hub at the premises as efficient a
manager of bandwidth as I can and place the
intelligence where it makes the most sense. Some
things are better done on a shared or virtual basis."
No matter how such issues are resolved, carriers of
every stripe can expect to be developing and
delivering IN applications that largely parallel the IN
and SS7 capabilities in the PSTN for the next three
to five years, says Scott Wharton, senior marketing
manager for service providers at VocalTec
Communications Ltd. (www.vocaltec.com). After
that, he says, the momentum behind feature
provisioning and network functionality control within
the IP domain will outstrip traditional IN to the point
of decoupling the two.
"As more intelligence is built into the gatekeeper, [IP
telephony] providers will be able to go beyond the
limitations of the current system, but that will take a
while," Wharton says. "We'll see unified messaging
and multimedia capa-bilities combined with open
APIs (application programming interfaces) that
represent something much more than can be done
today in the PSTN, not just a better version." In the
meantime, VocalTec continues to expand on the
features its gatekeeper can manage, offering support
for such enhancements as call-waiting and follow-me,
wherein users input call routing instructions through
the web browser.
"One of the great advantages of developing features
for IP networks is that, unlike the PSTN, you don't
have to spend months on a project, then implement it
on your switches and start offering it commercially
before you're able to determine whether there's a
market for it," Wharton notes.
While VocalTec is already implementing features it
expects to be part of version 3 of H.323, it will take
a while for issues to be worked out before the
current version 2, only now going into commercial
release, is superceded at the standards level,
Wharton notes. Consequently, VocalTec and
everyone else seeking to respond to early carrier
demand for IN solutions will be pushing the envelope
with proprietary solutions that may or may not end
up being standardized.
"SS7 exists as a standard today, which gives us a
good base to work from in addressing immediate
needs," Wharton says, noting VocalTec has forged a
partner-ship with ECI Telecom Ltd.
(www.ecitele.com) of Israel to su ply the expertise it
needs to begin adding SS7 features to the
gatekeeper (Sounding Board, May/June). "This is
why the key standards issue to resolve right now is
the one we and many other entities are working on
with regard to the interfacebetween the gatekeeper
and IN."
Another company tapping even more directly into the
existing SS7 infrastructure is Ericsson
(www.ericsson.com), which is basing initial
implementation of features such as the three-call
conferencing service offered by Delta Three Inc.
(www.deltathree.com) this summer on direct
importation of IN capabilities from PSTN switches
into the IP cloud through the gateway.
"We are creating SS7 interfaces in our gateways that
allow us to talk directly to the legacy system," says
Karen Cook-Hellberg, product manager for IP at
Ericsson. "Inside the gateway we employ SCP-like
nodes and use the same multilayer architecture of
SS7, so that there's complete transparency from one
side to the other. This allows the end office in the
PSTN to talk directly to the control point inside the
IP network."
But, beyond this point, Ericsson is still deciding how
to evolve the architecture, Cook-Hellberg notes.
"We're thinking through the extent to which we move
to IN implementation within the IP framework on a
standalone basis vs. the extent to which we access
IN in the PSTN from the IP side," she says.
New Avenues
Much of this uncertainty might disappear if the
strategy pursued by Lucent Technologies Inc.
(www.lucent.com) turns out to be a winner. Lucent,
with a vast imbedded base of Class 5 switches to
protect, sees a way, through its elemedia
(www.elemedia.com) division, to make those
switches a part of the IP networking domain on a
scale that would render the debate over whether to
locate IN inside or outside the IP network more or
less moot.
"Everything we do is focused on carrier-class IP
voice systems that will be able to support thousands
and, eventually, hundreds of thousands of
simultaneous calls through a single gateway," says
elemedia president Joseph Mele, Jr.
Mele says elemedia's strategy entails building toolkits
that allow applications developers to create
carrier-class IP-telephony products that can handle
all the billing, SS7, OSS (operations support system)
and other tasks required by telephone companies
while using software to eliminate the need for any
hardware adjuncts to either the H.323 server or the
Class 5 switch, depending on which machine is in use
at any network point. This means that, if elemedia
succeeds, the software performing all these functions
as well as the basic H.323 functions will be able to
work on Class 5 switches, thereby turning the
imbedded computerized switching systems into
high-end IP gateways, Mele says.
"We currently support voice and fax and by the end
of the year we'll build in a soft modem for data [at 56
kilobits per second]," Mele says. "And we'll have
soft modem support for ADSL.Lite in the first half of
next year."
These "soft modem" capabilities mean that signals will
be formatted at the switch using the imbedded
computing power rather than requiring separate
modems. Eventually, Mele adds, elemedia will
introduce a software conversion component for
ATM packets coming in over the ADSL or other
lines, making it possible to perform an IP-to-ATM
conversion or vice versa at the gateway server
without use of an ATM module.
Mele says elemedia is in discussions with Bellcore
(www.bellcore.com) about the possibility of
partnering to bring Bellcore's expertise in OSS and
IN into the mix. Bellcore, as previously reported,
plans to bring a carrier-class IP gateway/gatekeeper
suite to market this fall fully equipped to deliver IN.
Sources say Bellcore's IN solution will be part of the
software system Bellcore is supplying to Sprint for
ION.
Clearly, Lucent and Bellcore are in sync as is much
of the telecommunications industry on the goal of
achieving complete transparency between the circuit-
and packet-switched domains on the voice side while
bringing all the advantages of feature flexibility that
comes with IP technology. But, equally clearly, even
the most ambitious purveyors of packet telephony
will have some serious planning and experimentation
to go through before they can be confident that they
are choosing solutions that will stand the test of time.
Fred Dawson (dawson@albany.net) is a
contributor to Sounding Board magazine.
Copyright c 1998 by Virgo Publishing, Inc.
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