"What is a PBX?"
PBX is an acronym for Private Branch Exchange.
A PBX:

• Allows you to manage telephone and video calls that come into your company.
• Enables the use of a receptionist ensuring that all calls answered professionally and are routed to the most appropriate resource.
• Allows many telephones or videophones to share a common trunk allowing you to order a bulk line package from your telecom provider meaning lower costs.
• Offers extended telephone functions such as hold, forward, transfer and conference allowing staff to work together as a team when handling incoming calls.
• Provides toll bypass capabilities- where the PBX can be programmed to use an alternate route for long distance calls or where the PBXs are trunked together over long distances to reduce call costs.
• Includes voice and video mail to extend the availability of staff out of hours or when occupied.
• Supports out of hours policies. Calls are forwarded to an automated attendant outside normal working hours.
• Features hunt and ring groups to allow a large number of incoming calls to be managed among a group of staff on a first available basis.
• Queues callers allowing them to wait for agents who are currently occupied or unavailable.
• May optionally include ACD (Automatic Call Distribution) on the contact centres to allow supervised and managed call feeding into office or home based call centre staff.

"What advantages does an IP-PBX offer over a traditional telephone system?"
Quality. Digital encoding and transmission from the phone to the line make installation and cabling simple. Older PBXs required gain adjustment for each extension depending on the length and quality of the wire.

Open Standards. IP-PBXs run on an open SIP protocol. This means easy interoperability and the ability to shop around for the best of breed or best value handsets, peripherals and accessories. Older PBX systems featured dedicated handsets, line cards, etc.

Able to run future applications. SIP can support video, audio, messaging, meeting invites, video mail, presence, conferencing, etc. A SIP PBX will allow all of these applications and more as you need them.

Information. Using the same physical network as a company's computers allows integration to allow caller information to integrate with CRM systems, soft PC clients on laptops, etc.

Flexibility. A wide choice of different service providers are available and using IP they don't need to be local. Long distance intercompany call costs can be reduced by trunking PBXs together.

"What are the disadvantages of an IP-PBX?"
The handsets (IP Phones) are more expensive than conventional analog phones. Business handsets for conventional TDM systems were priced similarly. Over time the costs are becoming closer. Existing analog phones can be reused by using an inexpensive adaptor called an ATA. Or inexpensive PC soft client software may be used.

Critical voice traffic is sharing the same network as your data and may be degraded. A switched Ethernet network minimises the impact of large file transfers on the voice traffic. Provisioning enough WAN bandwidth if this is used and using QoS techniques like IP Precedence allows the prioritisation of critical voice traffic over data.

There are issues with firewalling and security to overcome, however the IP-PBX presents a solution to firewalling issues rather than a problem. At the most basic level calls may be made through local phone line connections.

"What are the basics that I need to implement an AuPix video PBX?"
PBX system
Systems are sized for the number of client devices in your company.
AuPix offers 2 standard sizes:

• 5 video and 15 total calls, 30 registrations
• 10 video and 30 total calls, 60 registrations, MCU
• Up to 200 users available on request.

UPS system
The ambient power consumption of the systems is 100W for the VPBX-1220 and 200W for the VPBX-2440. Approximate UPS sizes for different run times are as follows:

These figures exclude power consumed by telephones, switches and routers also required to maintain service.

IP Phones
These are audio only IP phones that are available from a number of different vendors. The IP phones need to support the SIP protocol and preferably feature programmable keys so that the dial strings for hold, transfer, conference etc. can be programmed. IP phones that support both G.711 and G.729 audio codecs are preferable but the PBX is capable of transcoding so G.711 only phones can be used. Power over Ethernet may be desirable to allow simple cabling to the phone and resilient power. Phones that can download their configuration using TFTP may be simpler to manage in larger deployments.

IP Videophones
IP videophones used on the internal network preferably support the SIP protocol and SIP features such as hold, forward, transfer etc. Phones that can download their configuration using TFTP may be simpler to manage in larger deployments.

Contact Centre videophones or PC clients
The Contact Centre supports the ACD feature and this requires a contact centre client device to allow logging into and out of various queues and extended call handling features.

A switched Ethernet network
Older networks may still use Ethernet hubs. A VoIP deployment requires Ethernet switches.

Connection to the Internet
It is typical for companies to choose a 2Mbps connection for 5 - 10 videophones using a symmetric leased line or SDSL connection.

Access to PSTN network.
Access may be through an external service provider or using direct line connections on your premises. If this type of connection is desired an analog or ISDN card option will be required when ordering.

"What makes the AuPix PBX different to other systems?"

• It works with video clients as well as audio clients.
• It is provided with the cards installed and the software loaded- ready to go!
• It may be configured through a web browser.
• The MCU feature - For video conference calls between several people or groups of people. This works in switched mode with up to 9 way continuous presence available soon at no extra cost on the VPBX-2440. To enter an MCU call just dial *45!
• User programmable interactive video response (IVR)- where the user may record video clips and determine the sequence for handling incoming calls.
• Video Relay Service (VRS) option- allowing a number of agents to simultaneously conference between a number of video and audio devices. Used for sign language interpretation.
• Contact Centre option. For organisations receiving large numbers of incoming video calls a contact centre allows incoming users to queue into the next available agent, and for agents to log in and out.
• APS-50 PC Video & Audio Client software option- This allows laptop users complete mobility from most home wi-fi networks and hotspots.
• Wide compatibility. The system is tested with all of the major video and audio handset vendors.
• Detailed call records that may be exported for auditing, billing and review.
• Interactive video queue messages with text prompts may be customised with your logos etc.
• It may be customised for your application. Aupix Ltd offer high-value development options.

"Do I need a PBX to make calls between video clients?"
No. Video clients can make peer-to-peer calls using an IP address. The PBX overcomes a number of the problems encountered when calling directly from one video client to another as follows:

• No need to disable the firewall in the client location.
• Reduced issues with firewall traversal.
• IP addresses assigned using DHCP may change without losing communication.

"Can I make telephone calls to ordinary telephones from an IP videophone?"
Yes, the IP-PBX can act as a gateway enabling calls between an IP telephone or videophone and analog telephones and mobile phones.

"Why are there different numbers of users on the different PBX models?"
Audio PBXs (including the AuPix PBXs) may handle hundreds of audio clients. Video is much more processor-intensive and the different models have been carefully performance benchmarked to assure consistent quality, speed of response, and reliability. The systems are sized by the number of video client registrations and the number of concurrent video calls (meaning the number of live video calls at any time). The models launched support limited numbers of video clients, however if much greater numbers are required a tailored solution is available from AuPix.

"What upgrades are available for the systems?"

VPBX-1220
AuPix can offer a trade-in for this system if you wish to upgrade to a more powerful model.

VPBX-2440
This may be upgraded to support a greater number of clients.

All Models
PBXs may additionally be trunked together for greater capacity. Line cards may be upgraded to support larger and different trunk options. The upgrade requires a return to base or an engineer visit.
The line card options are as follows:

• 4 line analog line card for 4 simultaneous calls
• 4 BRI line card for 8 simultaneous calls
• PRI line card for 24 (T1) or 30 (E1) simultaneous calls
• Ethernet trunk card for calls limited by WAN connection speed

Additional licences are available for systems requiring G.729 transcoding.

Optional extras on request include an H.323 video gateway, ACD, and Video Relay.

"What support options exist for the appliances?|"

The system is shipped pre-configured and includes a quick start guide to allow IT engineers to self-install the system, and a built in help system for reference information. An included CD also containss a manual in PDF format for printing.

A range of default users are pre-configured to allow rapid installation. AuPix will also apply any settings you request at the time of ordering free of charge.

Web configuration
The system is configured through a web browser and has an in-built user manual.

Quick start
A 1 hour quick start option allows you to have the system configured by an AuPix engineer remotely.

4 hour support package
A 4 hour support package is available for in-depth issues or long-term support.

Upgrades
Free software upgrades are available for a period of 1 year after shipment of the PBX.

"Which protocols and codecs does the PBX support?"
The PBXs use the SIP protocol but the VPBX-2440 also includes an H.323 gateway for audio or video calls.
The PBX switches audio and video traffic so is transparent to the audio and video codecs when working between end devices.
If a client connects to the PBX's interactive voice response system, the G.729 and G.711 codecs are supported.
For interactive video response, H.261, H.263 and H.264 video codecs are supported.

"Will the PBX continue to work in the event of a power cut?"
Yes, assuming that the following components are protected by an uninterruptible power source:

• Router
• Switches & Hubs
• Phones

"Will the PBX restart without assistance in the event that power is lost?"
Yes.

"Can I use phones attached to the PBX to call emergency services?"
VoIP cannot be relied upon for connections to emergency services. Additionally the emergency services may not have a mechanism to trace the caller's number. It is recommended that an analog telephone is retained for these calls.

"What type of carrier connections should be used with the PBX?"
It has been typical over recent years to use a local ISDN or PSTN line connection for regular voice traffic and incoming calls. The contention ratio for the number of lines vs. extensions may be based upon historic data or an existing policy. An Internet connection utilising a SIP trunk may be used to connect to additional service providers or in order to trunk between the PBX systems. The criteria for sizing the lines are based on:

• Number of concurrent video calls (5 or 10 for the VPBX-1220 and 2440).
• Video call bandwidth (default 384 kbps).
• Number of concurrent audio calls over the WAN (G.729 @9kbps/connection).
• Average WAN loading for regular data traffic.
• Headroom. 20% for IP packetization + 20% extra headroom.

"What ISDN lines should I order?"
For a single ISDN BRI choose one with the following options:

• CLI (to identify the caller's number)
• DID (To identify the number called by the caller)

The BRI ISDN cards used support the ETSI standard and use the S-Bus ISDN interface.

For PRI connections contact AuPix for further information.

"Will the PBX run straight out of the box?"
Not unless the administrator has provided all configuration information to AuPix prior to shipment. An electronic configuration form is available on request to enable this. The system needs to be configured with a minimum of an IP address, trunk line numbers, extensions and user I.Ds before it is ready to make calls.

"Is the system suitable for direct connection to the public Internet?"
The PBX is a hardened appliance designed to connect to the public Internet. A private network connection is also provided.

"Can the system be configured in a resilient way?"
Yes. Multiple systems may be configured in failover mode to minimise the risk of unavailability. Contact AuPix for further details.

"Should the PBX be installed on the public Internet, behind the firewall or in a DMZ?"
AuPix recommends for maximum availability that the PBX system is connected to the public Internet. This prevents mechanisms such as PAT, NAT, etc. from interfering with the video communication. Video devices may connect to the PBX through a stateful firewall.

"Why does the PBX have a front LCD panel?"
The PBX is capable of continuous unattended operation. The front panel indicates the current status including IP addresses, interface states, time, CPU loading, and network loading. It is particularly useful for the first installation in order to find out the IP address of the system for configuration.

"Can I restart the system without an attached console?"
There are 2 silver buttons to the right of the VPBX-1220. The larger button when pressed once will perform a clean shutdown. Press it again to turn the appliance back on. The small silver button is an emergency reset button and should only be used in the case that the system cannot shut down using the larger silver button.

"How can I find out if my video and audio endpoints are compatible with the PBX?"
AuPix continually tests the system with industry-leading video and audio clients. A compatibility chart is available on request.

"If I change PBX system can I retain my old business telephone numbers?"
In general, yes you can if you either retain the old analog or ISDN lines, or ask your service provider to provide a solution on the new line using the old numbers. If moving to a new provider the old provider will need to authorise the handover of the numbers to the new provider.

"Is the PBX system compatible with other telephones and systems?"
Yes. It is built on the industry standard H.323 and SIP protocols.

"Does the PBX degrade or delay the audio and video?"
No. The PBX can improve quality by limiting the number of connections supported by a trunk to prevent it from becoming oversubscribed.

"Is there a reference design or white paper to show how a typical deployment might be made?"
Yes. Please contact AuPix for a copy.