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VoIP (Voice over Internet Protocol)

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IP-PBX (Internet Protocol-Private Branch Exchange) systems provide telephone services that mimic traditional PBX systems delivered over LAN (Local Area Network) topologies

This type of system is similar to computer network topologies and utilizes much of the same hardware to deliver phone service

VoIP allows both voice and data communications to be run over a single network, which can significantly reduce infrastructure costs

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Because of the bandwidth efficiency and low costs that VoIP technology can provide, businesses are migrating from traditional copper-wire telephone systems to VoIP systems to reduce their monthly phone costs.

In 2008, 80% of all new PBX lines installed internationally were VoIP

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Here is an example of an IP-PBX VoIP system

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IP-PBX systems are packet based voice technology for the interfaces between internal trunks, stations, buses and the internet

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Many of these systems include devices such as gateways, routers, switches and servers that are integrated into an existing data network

This eliminates the need for separate voice and data networks.

All network cabling is treated as data only, which means that both voice and data cabling is terminated on patch panels as opposed to termination blocks

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VoIP systems employ session control protocols to control the set-up and tear-down of calls as well as audio codecs which encode speech allowing transmission over an IP network as digital audio via an audio stream

Session control protocols are some what similar to performing on-hook and off-hook conditions for legacy phone systems

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Audio codec refers to a single device that encodes analog audio as digital signals and decodes digital back into analog. In other words, it contains both an Analog-to-digital converter (ADC) and Digital-to-analog converter (DAC) running off the same clock.

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VoIP phone with built in ADC

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The purpose of the audio codec software is to represent the high-fidelity audio signal with minimum number of bits while retaining the quality.

This can effectively reduce the storage space and the bandwidth required for transmission of the stored audio file.

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A major development that started in 2004 was the introduction of mass-market VoIP services that utilize existing broadband Internet access, by which subscribers place and receive telephone calls in much the same manner as they would via the public switched telephone network (PSTN).

Full-service VoIP phone companies provide inbound and outbound service with Direct Inbound Dialing.

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It is becoming increasingly common for telecommunications providers to use VoIP telephony over dedicated and public IP networks to connect switching centers and to interconnect with other telephony network providers; this is often referred to as "IP backhaul".

Smartphones and Wi-Fi enabled mobile phones may have SIP (Session Initiation Protocol) clients built into the firmware or available as an application download.

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Communication on the IP network is inherently less reliable in contrast to the circuit-switched public telephone network, as it does not provide a network-based mechanism to ensure that data packets are not lost, and are delivered in sequential order

VoIP implementations may face problems mitigating latency and jitter, especially in the early days of implementing VoIP solutions.

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One of the ways to address latency issues on a VoIP system is to use QoS (Quality of Service) protocols that give voice packets priority over data packets.

VoIP solutions are also susceptible to power outages unless the whole data network is on a standby power system such as a UPS or back up generator

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A small UPS

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Let’s take a look a some specifications for a VoIP system to get a better understanding of what IP-PBX system can do and what features they offer.

We’ll use the Allworx system shown in an earlier slide….

The following slides show the specifications from their web site

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• This Bundle Includes 1 - Allworx 9112 Phone and 7 - GXP-2000 Phones

• Designed for companies with up to 30 users, the Allworx 6x system is a state-of-the art communications system that integrates three essential business operations into one simple system. It is a feature-rich phone system, a robust data network system and a message center that substantially improves productivity.

• With the Allworx 6x costing less than $500 per user (for a 20-person business), you can have it all... why compromise?

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• You can simultaneously use both analog and VoIP phone connections as you control the pace of your transition to new technology.

• More analog ports in the base connection of any manufacturer allow you to control when and how you move to VoIP.

• Features can be activated by you when you are ready to use them for your business. When you are ready to take advantage of VoIP you can do so seamlessly without disrupting your business operations.

• Add remote users when you need them without any hassle.

• Connect multiple offices to make one large organization.

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Some of the other features offered………..

• Calls will continue to work like your traditional telephone system, and appear in the same way.

• Keep some of your analog lines for fax and 911 calls and use VoIP lines to save money on long distance calling (requires VoIP via WAN option).

• Up to 30 users can use VoIP phones (up to 2 analog devices also supported).

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• Intercom capability across the platform. • Use a Single Inbox for all messages! Respond

to your voicemail on your computer (requires Message Center option).

• Set up Conference Calling for up to 8 seats. • Use Group Calendaring to be more efficient

(optional license)• Create a Virtual Private Network (VPN) for

the ultimate in secure transfer (optional license)

• Set up Call Queuing for a call-center presence (optional license).

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Allworx Call Assistant allows operators or receptionists to easily manage incoming calls, track key phone lines and individuals or groups. It is an easy, intuitive, fully integrated software tool which works in combination with any Allworx VoIP phone (optional license).• Set up a Door Relay for increased security at your

office. • Leverage the Allworx built in PC network to

manage your data communications across your business - from PCs, printers, VoIP phones, servers and backup systems.

• Compatible with VoIP Phones that follow SIP protocol• Compatible with Softphones, including Pingtel Instant

Expressa, EyeP Media and xTen

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• Supports G711 and G729 endpoint connections

• Compatible with ITSPs (Internet Telephony Service Provider)

• LAN file server: MS Windows compatible via SMB/CIFS (Server Message Block) protocol

• Email Server: POP3 and SMTP

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• It uses the latest VoIP technology and can be configured to operate in traditional "key system" or enterprise "PBX" modes. You can mix and match Key and PBX functionality per phone.

• The Allworx 9112 VoIP phone comes with 12 Programmable Function Keys (PFKs). These keys can be programmed to show line appearances, call appearances, speed dial, BLF (busy lamp field, DSS (direct station select), Centrex flash, headset and redial.

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• Support SIP (RFC3261), TCP/IP/UDP, RTP/RTCP, HTTP, ARP, ICMP, DNS (A record and SRV), DHCP, PPPoE, TFTP, NTP

• Support NAT traversal (STUN, etc), server fail-over, SIP presence (SIMPLE), and more

• Multiline support of up to 11 lines indicators (expandable to a few dozen more through expansion key-module)

• Graphical LCD to display up to 8 lines and 22 characters per line

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• Dual 10/100Mbps Ethernet ports • Headset jack • Support Caller ID display or block, per

call or permanent • Call waiting, Hold, Mute, Transfer

(blind or attended), Forward, and more • Multi-party conferencing • Integrated Power-over-Ether (802.3af)

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Notice the 6 outside phone lines (6x)

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Notice the various RJ ports

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There are many different types of IP-PBX or VoIP systems at there that provide many of the same features that we just looked at

Many of the specifications address networking protocols and standards that we will discuss in later lessons

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