Part 3: IP Telephony

IP telephony (Internet Protocol telephony) uses the “Internet” to transmit voice and fax instead of connections over public switched telephone network (PSTN) lines. IP telephones are connected to an ethernet network to communicate internally and externally. IP Telephone systems revolutionized the telecom market by allowing a single dedicated network jack to connect both the user’s computer and telephone.

I looked up the internet to find the history of the IP Telephone and two different stories exist out there. The first one is that Selsius Networks created the first IP Telephone and was eventually acquired by Cisco. According to Wikipedia, the first commercially available IP phone was the Selsius 30SP. In November, 1997 the company sold five 30SP phones to the TRI lab of Southwestern Bell in San Antonio. The company was acquired by Cisco in 1998 and Selsius provided the evolution path to most of the Cisco phones you see today on desktops throughout the world.

The second story is that Nortel Networks or Northern Telecom was experimenting with Unistim IP phones prior to 1997, with the first Nortel IP Phone (i2004) introduced commercially in 1998. Unlike the Cisco’s phones which were largely developed out of data and networking, Nortel’s IP phones were developed out of telephone and voice technology. While Nortel may have been a little late to the IP phone rollout to desktops throughout the world, they were very successful and achieved parity with Cisco in the number of IP Phones rolled out. Many legacy Nortel IP sets are still in service today (being supported by E-MetroTel and Avaya) and are operating on desktops with the most current technology.

What are some advantages of IP telephones compared to digital and analog sets?

1. Before IP telephones, a dedicated voice jack needed to be kept at each desk or anywhere you wanted a telephone. With IP telephones you can use the same ethernet jack for your desktop phone and computer.  This saves on installation, complexity, and wiring.
2. Unlike digital and analog telephones, IP phones can run on Wi-Fi networks and do not need any cabling at all. This can be achieved through soft phones on a computer that use the Wi-Fi network to send and receive calls, or by using a Wi-Fi to RJ45 converter. The Wi-Fi to RJ45 converted takes the Wi-Fi signal and turns it into a wired LAN jack that allows you to connect an IP phone to the network without having to run any cabling through the walls. Newer IP phones are also Wi-Fi capable devices that work directly with the Wi-Fi networks.
3. While most business grade digital and analog telephones have superior audio, IP phones have been extensively engineered to deliver the latest in audio technology such as crystal clear HD voice on both handset and speakerphone options. The phone usually possesses a large display that can be backlit, color, or black and white. Some IP phones have also introduced touch screen technology to allow you to select features and press buttons virtually on a touch screen.
4. Unlike most digital and analog telephones, (with some exceptions of Centrex and Meridian 1 digital telephones) that need to be connected directly to the main KSU or PBX, IP phones can be remotely connected anywhere via a LAN connection. For example  if your business is based in Toronto, you can give IP telephones to your employees working in Tokyo, London, Chicago, Seattle, Moscow or anywhere else an IP connection exists. They can be thousands of miles away, but their telephone will appear to be in the main Toronto office and users can dial internally between each phone anywhere in the world.
5. IP Phones tend to have a heavier, sturdier and more state of the art look than conventional telephones. Most IP Phones today have a large logo of their brand on the back of the phone and a decorative rear foot stand that looks pleasing to anyone sitting and facing the back of the phone.

IP Telephony does have some drawbacks or limitations:

1. Close attention should be made to the state of your existing LAN before you choose an IP telephone system. If you are still on a slower speed ethernet and/or are experiencing congestion, it would be best to upgrade your network prior to moving forward.  Likewise, if the Internet service in your serving area is “lacking”, you should consider upgrading or waiting until higher speeds become available.
2. IP phones share network bandwidth with computer data and will require Quality of Service (QoS) monitoring to ensure performance is not affected. From a security perspective, it is also vulnerable to network attacks just like computers. Digital and analog phones on the other hand are on a separate telephone network and will still function even if the computer network is down.
3. Unlike conventional telephones, where a single pair of cables can control everything from the display to the speakerphone, IP Phones need to be connected to a Power over Ethernet (POE) switch or a wall powered power brick.  This is especially true for powering features like the color backlit display or high quality HD voice.
4. IP phones tend to be much more expensive than digital and analog telephones.

Operation:

IP phones run on many different protocols. Cisco uses SCCP and SIP, legacy Nortel uses Unistim and SIP, while Avaya uses H.323 and SIP. Various software versions and firmware are available for these phones that will allow users and administrators to flash different firmware to the phones. For example if you have a Nortel Unistim set that you want to convert to SIP for use on an IP Office, you simply obtain the SIP firmware from Avaya’s website and then use a TFTP server to upload the SIP firmware to the Unistim phone.

What’s the difference between IP Phone and IP trunks?

IP trunks use the same internet based protocols such as SIP to provide VOIP PSTN service (instead of analog or digital PRI’s) to telephone systems. You don’t need IP phones to run on IP trunks. Conversely you don’t need IP trunks to run IP Phones. For example, if you buy a Nortel BCM50 system with 30 IP sets, it is possible to use analog POTS trunks on the main system for incoming and outgoing trunk calls. The IP based technology only exists internally on the networks.

On the other hand, you can buy an Avaya IP Office with 50 digital sets and use VOIP trunking for incoming and outgoing calls, without having an actual IP phones active on the system. In this case IP based technology is only used externally on the network.

Lastly, you can have a system such as the E-MetroTel UCx where you have digital, analog, and IP phones on the same system and a mix of analog POTS and IP trunks on the same system. Programming on the system can allow certain lines to use analog for incoming only or IP for outgoing calls only. Systems with this type of flexibility are commonly referred to as a full IP-PBX.