How to Tell if You're Ready to Deploy Converged Communications

By Richard Garboski  |  Posted 2008-07-16 Print this article Print

=How to Get to Converged Communications}

How to Get to Converged Communications

One of the easiest first steps to unified communications is through an application called SIP trunking. Offered by many service providers, SIP trunking bridges the gap between those using VOIP and those still on the PSTN (Public Switched Telephone Network). It is often seen as a gateway to shifting telephony to IP because it can be very simple to deploy. Plus, it can produce immediate (and radical) cost savings. In-depth background on SIP trunking can be found at the SIP Trunk Network.

Unlike in traditional telephony, where bundles of physical wires were once delivered from the service provider to a business, an SIP trunk allows a company to replace these traditional, fixed PSTN lines with PSTN connectivity via an SIP trunking service provider on the Internet. With SIP trunks, it is no longer necessary to purchase ISDN, BRIs, PRIs or local PSTN gateways.

There are three components to setting up a secure SIP trunk connection:

1. An IP-enabled PBX.

Newer PBXs usually have IP technology built in. If your PBX is not IP-enabled, MGCP, H.323 and SIP are all protocols that can be used to do so. However, SIP has a number of advantages that the other protocols do not. The most important advantage of SIP is that it supports rich communication (while, for example, H.323 is a voice-only protocol).

2. An edge device that can handle the traversal of SIP traffic.

The enterprise edge component can either be a firewall with complete support for SIP or an edge device connected to the firewall, handling the traversal of the SIP traffic. The majority of current firewalls and NAT-routers are not designed to handle full person-to-person communication, which will not reach users on the LANs unless the enterprise firewall has specific SIP support. SIP traversal of firewalls and NATs is becoming a commodity in the sense that most vendors advertise support for the protocol. However, the basic SIP support offered by most of these vendors does not have the richness of features to fulfill the needs of a complex enterprise environment. It is critical that IT managers evaluate their current firewall solution to ensure that there is proper SIP support when new firewalls and NAT routers are installed.

Edge devices, such as the SIParator from Ingate, are what we usually recommend to customers, as they solve these problems and more - while adding critical features such as:

-Handling, and resolving, interoperability issues between the IP-PBX and ITSP

-Reliability when adding survival features (i.e., failover for VOIP, etc).

-Security when taking SIP traffic outside the enterprise and transporting it over the public Internet to other networks or service providers. The security aspects of eavesdropping, call hijacking and call spoofing need to be addressed. The edge device can incorporate TLS (Transport Layer Security) which encrypts the signaling stream. This enables all the important setup information to be kept private over the public Internet. It can also support SRTP (Secure Real Time Protocol) which encrypts the voice, video and other media packets. Using TLS in combination with SRTP secures the communication, making it almost impossible to eavesdrop on.

-The edge device can also firewall the LAN, as well as the SIP traffic, serving as an all-in-one security component of your network.

3. A SIP trunk from an ITSP.

A traditional voice telephony service provider typically offers one or more T1/E1 trunks to the enterprise for fulfilling its needs for voice communication outside its own premises. The service provider is then connected to what is sometimes referred to as the world's biggest machine: the worldwide PSTN. Connectivity between the networks of the different service providers that constitute this "machine" is achieved by bilateral interconnect agreements between the various service providers. There are also wholesale service providers that aggregate the traffic from several local service providers and make the interconnect agreements for all of them collectively.

The SIP trunk offering is just another way of connecting the enterprise subscriber to the network. The interconnect and wholesale aspects remain the same. With an SIP trunk, the traditional T1/E1 interface ("trunk") is replaced by an IP-based connection that runs over the Internet connection to the enterprise. Nowadays, most enterprises already have such a connection to be used for their data traffic. As a SIP trunk is software and IP-based, it is much easier to manage remotely and therefore cheaper for the service provider to maintain than the traditional connections.

Global Connectivity: The Widespread Adoption of Converged Communication

One of the goals in creating SIP was to facilitate global connectivity: everyone reachable anywhere, at any time. Converged communications presents the next stage in the telecommunications evolution toward global connectivity. Once embraced, the entire business community - from smaller start-ups to large enterprises - will truly benefit.

 Richard Garboski is president and founder of eTechHelp, a global technology and Internet services company that specializes in helping companies move toward converged communications. He can be reached at

Richard Garboski is president and founder of eTechHelp, a global technology and Internet services company that specializes in helping companies move toward converged communications. He can be reached at

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