Results tagged “office communications server” from IP Communications and Technology
As part of a continuing series on Office Communications
Server 2007, this article will discuss the product's native telephony
capabilities.
As I've asserted many times, Unified Communications (UC) is an architecture
that may include many functional components, enablers and features. Presence,
Unified Messaging, Click-to-Dial, Simultaneous Ring, and mobility are just some
of the attributes that are often associated with UC. All of those play an
important role in UC but the core functional component of UC remains telephony.
In the context of this article, telephony refers to all of the features and
functionality associated with an enterprise-class business voice service.
Modern telephony services are now IP-based, either in the form of a
premise-based IP-PBX, a hosted IP Telephony service or various hybrid models.
When Microsoft announced the release of OCS in the fall of 2007 there were many
who claimed that it signaled the end of the PBX and that IP-PBX vendors such as
Cisco, Avaya, Nortel, NEC, Siemens, Mitel and others would be seriously
impacted by Microsoft's entry into the VoIP market. OCS does have VoIP
capabilities, but for most medium to large enterprise, the product's native
telephony features and functionally is inadequate. OCS can integrate with
IP-PBXs to provide the telephony requirements necessary for business. However,
the integration is not elegant (in most cases it must be done via media
gateways) and other than basic telephony features such as call origination and
transfer, the bulk of the enterprise telephony functionality will be provided
by the PBX; not OCS.
What follows is a partial list of telephony features and functionality required
(or expected) by most medium and large enterprise that are not available from a
standalone OCS solution:
E911
E911(as a telephony feature) refers to the ability of a telephony system to accurately identify the
location of the 911 caller and to accurately deliver that information to the
correct emergency dispatch location. That can be tricky in the world of IP
Telephony since IP Phones can easily be moved from one location to another.
However, there are proven and reliable ways to address the challenge. While
there are a variety of approaches, all major IP Telephony vendors have E911
functionality natively or have integrated 3rd party products into their
solutions.
In some cases, it is acceptable to have one or more analogue circuits to
provide E911 functionality. Also, an IP-PBX system installed in a small office
may not require E911 functionality if it is connected to the PSTN directly
since the telephone company would take care of the 911 location and routing
functionality.
However, in any large enterprise environment, E911 functionality is mandatory.
I've heard the argument that whether E911 functionality is required or not is
based on regulatory requirements for the location in question: nonsense! A
telephony architect or implementer has a moral responsibility to ensure that a
caller can place an emergency call when needed and that the call will be routed
to the correct location with the correct information.
SIP Trunking
IP Trunking, commonly referred to as SIP Trunking (since SIP has become the de facto
signaling protocol), is a relatively new method of connecting IP Telephony
systems to the PSTN. Traditionally, and still the most common approach, IP
Telephony systems are connected to the PSTN via Media Gateways. These devices
also known as IP Gateways, PSTN Gateways or VoIP Gateways, convert VoIP from
the IP Telephony system to ISDN or analogue circuits from the PSTN.
IP Trunking has many advantages, over the gateway approach including the fact
that it can improve the quality of voice calls by reducing, or eliminating,
conversions from one audio encapsulation method to another. Other advantages
are cost, eliminating points of failure, maintenance and other advantages which
I have listed in one of my previous articles on the subject.
Remote Survivability
Remote Survivability refers to the ability of a site, geographically separated
from centralized call control or PSTN connectivity or both, to remain
functional even if the site becomes isolated from the rest of the telephony
system. For example, if the network link between a branch office and the IP-PBX,
located at a company's head office is severed, the branch office may have a
requirement for telephony services to remain functional. The level of required
functionality will be dictated by the business requirements. IP-PBX vendors use a variety of methods
to provide remote survivability to their IP Telephony solutions which involves
distributing some, or all call processing functionality and PSTN connectivity.
Music on Hold
Most enterprises expect their telephony systems to play music, or some other
source of audio, to callers when placed on hold or when a call is transferred.
It is a basic functional component of any legacy or IP-PBX. In fact, most
enterprise systems support Music on Hold from a variety of sources and in some
cases, custom audio announcements whose content may be based on geographic
location or other criteria.
Hunt Groups
A common feature of a PBX is the ability to have incoming calls directed to a
queue where calls will be answered by agents based on a variety of criteria
including but not limited to first available agent, least busy agent, round
robin and others.
Attendant Console
While becoming less popular, many organizations still require that a live
person process all incoming calls for an organization or an enterprise
department. An Attendant Console will usually support many incoming calls and
will provide the attendant with visual and audio prompts and queues to aid in
the efficient processing of calls.
Admission Control
Admission Control allows a telephony system to refuse call attempts or to redirect
calls when it detects that insufficient network resources are available to
provide a quality voice path. I've heard Microsoft representatives make claims
that Call Admission Control is not required, but for the reasons discussed in
this previous article, I disagree.
Standards
One of the benefits IP Telephony systems is that many vendors support industry
standards such as SIP for signaling, and CODECS such as G.711 and G.729. While
not perfect, interoperability among vendors has been steadily improving for the
last several years. As a result it is now possible, for example to install an
IP-PBX from one vendor and select lower cost IP Phones from a different
vendor. Not so with Microsoft since they have chosen to implement their own
spin on SIP and have chosen their own proprietary CODEC called RTAudio. To date,
the only supported OCS phones are a model by Nortel/LG and a model by Polycom.
Neither phone supports LLDP-MED, a link discovery protocol that can play an important role with respect to VLAN, DHCP and Power over Ethernet configuration. The proprietary nature of the product also excludes the possibility of using 3rd party softphones such as the very popular X-Lite.
Geographic Diversity
A benefit for many large organizations deploying IP Telephony is that the
any-to-any nature of IP networks allows IP Telephony systems to be designed
with a high degree of redundancy by separating the call control functions
geographically. The business continuity benefits of such architecture can be
very compelling. OCS does not support geographic diversity.
Conclusion
I remember when Cisco first got into the telephony market approximately 10
years ago. Relative to the features and functionality available from TDM-based PBXs
(not to mention service quality and reliability), their product had minimal
functionality. As a result, it took many years of product development for their
IP Telephony product to move beyond the early adopters and into the mainstream
marketplace we see today.
Microsoft will, I am confident, continually improve their telephony
capabilities, but like Cisco, it won't happen overnight. Meanwhile, the IP-PBX
will remain alive and well for quite some time. And while Microsoft adds
telephony features to OCS, the PBX vendors will continue to evolve and improve
their own products; both from a telephony and an overall UC perspective.
The PBX is alive and well. And while it will continue to evolve, the PBX and
its leading vendors won't be disappearing any time soon.
Rick McCharles
Unified Communications Practice Principal
RIC Services,
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