Using analog cellular phones for data computing

Analog cellular data computing should be considered a backup solution because analog inherently doesn't work as well as digital technology. However, analog cellular offers excellent coverage with service available in almost any city or town, and on most major highways in the US. For this reason, analog cellular will remain the only wireless data option in rural areas for quite some time to come.

While communicating data over analog cellular can work reliably, there are some unique items to consider. Instead of connecting your modem into a telephone line, you connect it to a cellphone. With the right modem and cellphone, you can interconnect these directly. Here is what you need to know:

• Throughputs. You can expect 9,600 bps throughput with a strong signal. Under optimal conditions 14,400 bps may be possible. Sometimes you may only get 4,800 bps. Using cellular protocols, your throughput may change dynamically to respond to operating conditions.
• Battery and Signal. You will get best results with a strong radio signal and with a cellphone battery that is not almost empty. It may help to hold the cellphone vertically with the antenna extended.
• Cellular Capable Modem. Use a modem that supports cellular protocols which include ETC, MNP10, MNP10EC, TxCEL and EC². These are special error correcting protocols. Modems that support these cellular protocols are generally promoted as cellular capable. Most come in a PC Card (PCMCIA) format.
• Cellular Protocols Enabled. Some modems automatically detect a cellphone connection and enable the cellular protocols. With others you have to either configure the modem for cellular operation (e.g. Windows control panel) or you have to add an AT command to the modem initialization string of applications. Operating information will be included with your modem manual.
• Cellphone. Not all cellphones can be used for data communications. Moreover, any cellular capable modem only supports specific cellphones. Check with the modem vendor for supported cellphones.
• Direct Connect Cable. You will need the right cable to connect the modem to the cellphone. These are sold either by the modem vendor or the cellphone vendor. There are also adapter devices that allow you to use non-cellular capable modems, but these are not as simple to use.
• Modem Pools. Using analog cellular protocols only works if the destination modem also supports the same protocols. Unfortunately, most Internet service providers, corporate modems and online service providers do not. Call the ISP or the destination modem organization if there dial in modem pools support cellular protocols. However, many cellular carriers have installed modem pools that translate between cellular protocols and conventional modem protocols. These modem pools are usually accessed by dialing *3282 (which spells out *DATA) as a prefix. Check with your cellular company for details as service details vary.
• Faxing. You can also use fax software to send and receive faxes. It is best to reduce transmission rates to 4,800 bps. Some fax software, e.g. WinFax has a cellular setting.

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