Frequently Asked Questions About IP Videocommunication

What data rates do SCOTTY IP video communication products support?

SCOTTY's IP video communication products support a range of data rates varying between a 32 kbps minimum for the mm156 through to 2 Mbps and above for solutions such as the mm745 browser videophone or Z470 PCI card.

What type of IP network do I need?

Any local area network (LAN) can support the needs of a few videophones. A switched 100Mbps network is desirable. The minimum speed of the mm146/mm156/CareStation 156s is 32kbps, and good fluid video is available at speeds around 96kbps, so a WAN connection with 96 kbps or above of continuous bandwidth is desirable.

IP videophones can be used across corporate WANs, VPNs, wireless networks, and broadband connections including ADSL, Cable, SDSL, Nx64, T1, and E1.

It is important to consider the impact of the use of videophones on a shared network with limited bandwidth. Facilities exist in all videophones to limit the call bandwidth available to the user.

Can I run other applications on the phone?

Various bespoke applications can be developed for all videophones. The mm745 series additionally supports Java applications and a web browser. If you would like to discuss your application please contact your SCOTTY group representative.

Do the videophones support fixed and dynamic IP addressing?

Yes. The videophones support static and dynamic (DHCP) IP addressing. The mm146/156/CareStation 156s videophones additionally support PPPoE (Point to Point Protocol over Ethernet), which delivers IP configuration on presentation of a correct user name and password.

How do I talk to the outside world?

There are several ways to talk to the outside world – via the IP network (as used for email, internet, etc), via ISDN, or via PSTN.

On IP only products a connection to ISDN requires a ‘gateway’ to be installed in the company’s IP network to allow connection to the ISDN network, or connection to a public gateway service. This gateway then converts from IP to ISDN and also from H.323 to H.320.

This makes it possible to call from an IP videophone to virtually any ISDN videophone or videoconferencing system, anywhere.

PSTN networks can be accessed directly from the mm156/CareStation 126s/CareStation 156s videophone, or via voice only or voice + video gateways.  Application notes are available to provide instructions on interfacing the mm745 with a PSTN gateway.

What are the issues surrounding firewalls?

In order to communicate with a phone outside the corporate WAN, it is necessary for the phone to be able to pass data through the company’s security systems. In order to do this, the firewall must be configured to allow video traffic.  mm146, mm156 mm150, and CareStation 156s models support three protocols- H.323, SIP (Session Initiation Protocol) and Packet Buddy™.

SCOTTY’s Packet Buddy protocol is designed to provide easy firewall traversal, and leverages port forwarding functions in the firewall to provide PBX-like facilities. Packet Buddy uses a single UDP port, meaning that the return stream to a call originated within the network is able to return without any specific rules in the firewall. To allow incoming calls just one port forwarding rule is required in the firewall.

If using the SIP protocol a Proxy is commonly used to provide a path around the firewall, and a public address without allowing direct access into the network from outside.  If using SIP directly between videophones, port 5060 is the call originating port, the video then uses the port(s) determined in the Network Setup menu (default 2099 – 2109).  No current support for NAT is available in the absence of a SIP proxy.

The H.323 protocol requires more detailed firewall configuration if using the public Internet.

The call setup (H.225) information uses TCP, and always uses port 1720. Because the initial reply comes in on port 1720 it is usual to get an answer from another H.323 system as long as there is a route to it. The systems then enter a capability exchange phase (H.245) where decisions are made on which audio and video standards should be used and which ports these will go out and return on. This uses TCP. Audio and video streams are then started.

These use even numbers, and the corresponding odd number contains RTCP information (Real Time Control Protocol).

A typical complete port usage is as follows:

1718 Gatekeeper auto registration UDP

1719 Gatekeeper Manual Registration UDP

1720 Call setup TCP

The following port range differs from manufacturer – manufacturer. mm745 port ranges start at 5000.

• 5000 Capability exchange (H.245) TCP
• 5002 Audio out UDP
• 5003 RTCP stream for audio out UDP
• 5004 Audio in UDP
• 5005 RTCP Stream for audio in UDP
• 5006 Video out UDP
• 5007 RTCP stream for video out UDP
• 5008 Video in UDP
• 5009 RTCP stream for video in UDP
• 5010 Bidirectional data UDP

Using an H.323 aware firewall eliminates the complications and the security risk of ‘nailing’ these port ranges open. The firewall looks at the call set up messages and dynamically opens and closes the corresponding ports automatically. The firewall also inserts the external IP address of the videophone into the H.245 messages as they traverse the firewall meaning that the videophone at the far end has the correct return address.

All that’s needed in this case is the identification of H.323 endpoints, e.g.

1. Create a group with IP addresses corresponding to videophones on the network.

2. Assign H.323 properties to this group.

3. Create a static IP address translation from the internal address to the external address for each videophone.

Using a non-aware firewall, such as a home router/firewall is reasonably simple.

Just create a DMZ (De-Militarised Zone) for the videophone. Also find out the external address for the home router/firewall and enter this in the NAT field of the videophone set up. This will allow the videophone to send the correct return address in it’s H.245 stream before it traverses the firewall.

To sum up, firewall issues generally manifest themselves as lost video and audio streams. If correctly specified and configured, firewalls can be made to work in harmony with H.323 and Packet Buddy video endpoints.

Can I make telephone calls to ordinary telephones from an IP videophone?

Yes, as long as there is a suitable gateway connected somewhere on the IP network. This may be a separate item, or it may be an IP-PBX. The mm156 and CareStation 156s additionally includes a direct PSTN line connection.

Can I make video calls to my company’s ISDN videoconferencing systems from an IP videophone?

Yes, as long as there is a suitable gateway connected somewhere on the IP network.

What IP-PBXs does it work with?

The videophones work with any IP-PBX that supports H.323. In many cases a gatekeeper is required to interface with the IP-PBX system. Please contact your SCOTTY representative if you would like information on interfacing to IP-PBX systems.

Does it connect to wireless LAN?

All IP videophones have been tested and work with wireless bridges from various manufacturers. The wireless bridge connects to the Ethernet port of the videophone.

Will the IP videophone work with H.324 (POTS) equipment?

The mm156 and CareStation 156s models work with H.324 devices. This allows a number of advantages.

• Buy now and install Broadband when it’s available – If you want video now but broadband networks are not yet available in your area.
• Fallback to audio/video calls over a telephone line.  At times when the broadband system is unavailable or congested.
• One size fits all - Make every type of telephone and video call from one device.

Can I make an ordinary voice call using this phone?

Yes. The phone supports VoIP (voice over IP) to the H.323 standard as well as video.

How can I connect an IP videophone to my home broadband line?

Please see the Technical Notes on the SCOTTY website for each product.

What does ‘Quality of Service’ mean?

IP networks have traditionally been used for carrying email, web content, and file transfers – all applications where a delay of a few 100ms or even a second or two is not a problem. When IP is being used to carry voice and video, it is critical that the information gets from one end to the other quickly, without delay – otherwise there will be a break-up of the speech or pictures. To allow such time-critical content to breeze though an IP network and jump any queues that emails etc may be waiting in, the network needs to be able to tell the difference between an email packet and a voice / video packet. Quality of Service (QoS) refers to the various different methods that can be employed to prioritise, measure, and ensure timely delivery of time-critical information. QoS mechanisms can be costly and time consuming to implement. Both Packet Buddy and H.323 protocols employ rate control mechanisms for use over non-QoS networks allowing users to immediately enjoy the benefits of toll-free video communication.

How do I call someone? i.e. what information do I need to know?

There are several options:

You will need to know either:

• The IP address for example 62.173.119.215 (permanent static IP address recommended)
• The StatIX group number and extension number for example 1123 4567890 (used over the public Internet when a static IP address is unabailable or too expensive)
• The E.164 number if using a gatekeeper for example 1 1234 567890 (often used in private WAN environments)
• The alias for example j.doe@acme.com (commonly used with the SIP protocol)

What is SIP?

Session Initiation Protocol (SIP) is the IETF (Internet Engineering Task Force) alternative protocol to H.323 for setting up and tearing down calls. It is proving popular today for the provision of Internet based messaging and voice.  SIP based video services are beginning to emerge. SIP and H.323 use common components such as video and audio codecs, and devices to bridge between the two protocols are available.

How can I participate in a multi-way videoconference?

Conferences are managed in a number of ways:

• Setup and management via web browser.  Web browsers are supported on mm745, Mobile, ProMax, and Warp products.
• By dialing into a conference number.  Supported on all models.
• By dialing a general number and navigating into the conference.  Using DTMF tones or Far end camera control.  One of the two above is supported across the range.

The majority of MCUs (Multipoint Control Units) available today support H.323 calls over IP and H.320 calls over ISDN. They are also capable of bridging between the two formats. You can use either own an MCU or subscribe to an external service from a conference service provider. IP videoconferencing reduces the cost of MCUs because there is no need for the MCU to support a separate physical connection for each participant- they all share a single IP connection into the MCU.