Vo IP
Considerations when implementing VoIP and UC solutions Migrating to UC By Jeff Kahn, Chief Strategic Officer, AudioCodes
Enterprises across the globe today are joining the growing trend of migrating their traditional TDM based telephony systems to IP-based voice and unified communications (UC) networks. There are many benefits to such a move including a reduction in operating expenditure from the merging of the voice and data networks as well the implementation of new converged voice and data services. While these make UC an attractive proposal, there are several issues that need to be considered to ensure any implementation is smooth.
Jeff Kahn discusses the issues and implications of migrating to UC systems.
Interoperability In most cases, the deployment of UC systems with VoIP services involves systems and equipment made up from many different vendors. Resellers and integrators often promote these multi-vendor systems as best of breed solutions that offer the broadest range of features and functionality. However, the drawback with multiple systems has always been the issue of interoperability. The interoperability between the UC
and VoIP elements in the network are determined by the Session Initiation Protocol (SIP), which has become the de facto standard protocol for real- time communications on IP networks. Any device supporting the protocol automatically communicates with any other SIP device. Problems have arisen as vendors have developed their own versions of SIP over the years. While they may be completely compliant with the SIP standard, many aren’t necessarily compatible with another.
Resellers can overcome this by making sure the UC equipment is fully interoperable. This may require lengthy testing, which some vendors might find unacceptable. Resellers can also choose to deploy a protocol mediation solution. The same issues occur with VoIP
data streams. Again different vendors may deploy different compression and packetisation algorithms (codecs) for transmitting voice traffic over the network. In some cases, where the two endpoints do not support the same codecs, an intermediary media transcoding device may be necessary to enable full interoperability throughout the network. Finally, legacy voice and fax
equipment can be integrated into the new UC environment using VoIP gateways that translate the traditional TDM traffic into standard VoIP protocols. VoIP gateways come in many different configurations, but can essentially be divided into two categories: small CPE devices for connecting analogue or digital phones, PBXs and fax machines and larger trunking gateways for connecting entire offices and networks to the public telephony network. The latter will still be required even in a fully IP-based UC environment to provide backup communications capabilities in case the data network fails.
Survivability One of the major benefits of UC is the ability to connect employees at remote locations or home offices to the main enterprise communications network. Remote workers, on the road, can be contacted at their office in just the same way as someone sitting in the company’s HQ. With the central UC control servers
UC connects remote employees to the main network. 26 NETCOMMS europe Volume II Issue 4 2012
all residing at the company HQ, what happens if a remote user loses their IP connectivity? There has to be a contingency, or remote office workers will end up without any communications until that link to the HQ is restored. To plan for such eventualities, it is important to select devices for the remote offices that support survivability. When deployed in a remote office,
survivable devices ensure that basic voice calls can continue between staff within the same office. And by deploying a VoIP gateway with a PSTN fallback mechanism, calls made to recipients outside the office can be automatically routed over the PSTN.
Security Perhaps the most critical issue when considering a move to UC and VoIP is security. Since UC and VoIP systems are IP-based and run over the same data networks as other enterprise data services, they are exposed to threats like denial of service (DOS) attacks, eavesdropping, fraud and VoIP spam. Other common data services can
be protected by standard firewall solutions. However, VoIP’s reliance on SIP makes standard firewalls insufficient for protecting UC networks, as they are unable to analyse the contents of the SIP messages, an essential requirement for identifying suspicious behaviour. A specialised application layer firewall device in the network, commonly known as an Enterprise Session Border Controller (E-SBC) is required. The E-SBC provides critical
features, such as call admission control, prevention of DOS attacks, topology hiding (i.e. concealing the internal structure of the enterprise VoIP network) and encryption of signalling and media streams. In a multi-vendor UC environment, the E-SBC allows different vendors’ systems to communicate seamlessly with each other, as well as providing security and enabling reliable connectivity to external SIP trunking providers. If we are to benefit from next
generation UC and VoIP systems then resellers and integrators need to ensure any deployment covers interoperability, survivability and security.
www.netcommseurope.com
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