© Communications©

Most communications providers refer to bandwidth when talking about data. Bandwidth refers to the amount of information that can be passed through a given connection, in most cases measured in Kilobits/second(Kbs) or Megabits/second(Mbs). The larger the bandwidth the more data can be passed through in a measured second and generally equates to a higher expense.

The following are a few of the more common services provided by the Telecommunications Companies (Telco) that go beyond your normal telephone line.

• ISDN - Integrated Services Digital Network
• Utilizes existing copper phone wires and has capabilities, @ basic rate, of 128 Kilobits/second. Most modems have a speed of 28.8 or 56 Kilobits. ISDN is becoming available on a fairly widespread basis. Start up costs are moderately expensive, ranging from $400.00 - $750.00. It is relatively inexpensive to use @ < 3¢ per minute on the average, but some communications companies offer flat rate services.
• It is great for Tele-commuting, video conferencing and on call applications for radiologists.
• Biggest benefit - it allows direct connections to a hospital network allowing archive access (technologist will not have to send old exams).
• Rural areas will pay dearly for this service if it's even available.
• T1 - T3
• Utilizes a network connection and consists of a leased line Utilizes a point to point connection. Speed range commonly starts @ 56 Kbs and well into the Mbs range. It is offered by all communications companies but can be very expensive.
• Cost is derived from usage and the distance between points of contact.
• The biggest benefit seen is speed yet is best utilized if one or two sites need to be connected.
• SMDS - Switched Multi megabit Data Service
• Utilizes a network design yet differs from T1 and T3 lines. SMDS is a service type connection that is time and distance independent. Speed ranges from 1.54 Mbs to 45 Mbs.
• Great if multiple sites, more than three, need access to a common facility. Each site can have customized bandwidth according to need.
• You pay for service access only, regardless of where you are within the local Telco area.
• SMDS is not available in all suburban areas and most likely is not available in the rural areas.
• Frame Relay
• ATM - Asynchronous Transfer Mode, instead of sending information in a continuous stream it sends it in cell packets. Packets allow faster information transfer because less information is sent for error correction purposes. Error correction occurs at the receiving end.
• Allows speed of 155 Mbs.
• This service is usually not available on a wide spread basis.
• Very few WAN applications are in use.

 

 
 
 
 
 

• Fiber Ring - A fiber connection available usually within a city network.
• The fiber ring gives true 100 Mbs connection and allows a self-healing network to be constructed. The user sees speed as if the LAN was being utilized.
• Usually this service is limited by the location of the site.
• Cost is sometimes less than any other highspeed connection.
• Fiber gives greater options for outside user connections.

Normal land-line connection is not always the best answer. Satellite and Radio-wave communications are additional methods and can transfer tremendous amounts of data. A satellite is usually way beyond the financial capabilities of most institutions but Radio is usually not. Radio-wave communications can offer significant advantages over leased line. There are some limiting features and requirements but over all the benefits outweigh the negative aspects. The points of connection must be in a viewable line of site, there can be no physical obstruction between sites and are somewhat distance limited. There are big benefits derived from having this ability.

• One time start up cost. The start up cost is comparable to setting up an SMDS or T1 line. No monthly service bills other than a maintenance contract for equipment.
• Additional sites can be added as needed at a known cost.
• Unlimited use and multiple functions. Can be used for teleconferencing as well as general information exchange.
• Annual savings over conventional leased lines can pay for the start up cost in the first year.