You are right about digital. However, the GSM digital encoding is drastically different from a modem encoding. Thus, conceptually at least, the mobile phone modem translates from your computer to GSM type encoding, whereas your "normal modem" translates from your computer to PSTN analog. WAP Phones and Integration
A WAP phone actually contains a Web browser program, which uses the Wireless Application Protocol (WAP). WAP has many protocols, including HTTP like commands, transmissions etc., etc. But, at the end of the day, it just turns your mobile phone into a web browser. This doesn't work very well in real life, however, because:
- you have to write very specialized web pages in WML, which no one wants to do unless someone is going to look at it (chicken and the egg)
- it's slow, really slow
- the display screens on mobile phones are very ordinary
- no one wants to pay for it anyway.
The speed of WAP is limited by radio frequency bandwidth. Your "normal modem" has an analog circuit all the way to the exchange. This circuit has 64K of available bandwidth. So, factoring in a bit of loss in the circuit, your modem can go at 56K. Today's mobile phone networks (of any flavor) were only ever designed to carry voice which is normally processed into about 8K, including overheads. Worse still, the actual available bandwidth is cellular in nature and must be shared between all simultaneous conversations. SO when you put your modem onto this transmission medium, no matter how hard you try, there just isn't enough bandwidth to go fast than 14K4. And, in real life, transfer rates of about 4-6K are typical. 3G wireless networks are supposed to fix this. I reckon it won't happen any time in the next 5 years. Think again about why you want remote access over a mobile phone, then reengineer the business process to work around it.
This was first published in November 2001