MobilePhone is increasingly taking on significant WirelessDevicesEnterpriseComputing roles. With SmartPhone and ThirdGeneration getting more mature, we are even seeing the day where MobilePhone can be linked up to satellites, and work in flying planes (if security concerns are overcome), etc.
See a mid 05 article on this at http://www.computerworld.com.au/index.php/id;1517809425;fp;16;fpid;0
Most mobile phones use GlobalSystemForMobileCommunication (GSM), although hybrids are coming out to ease the pain with global roaming. See http://news.com.com/2102-1039_3-5752926.html?tag=st.util.print
For best coverage, a quad band mobile phone is essential, as both European and North American triband phones provide limited use outside of their geographical area. The older dual bands offer increased coverage in a single country only.
Basic GSM frequencies
Single mobile phone that supports both CDMA and GSM networks are coming into the marketplace in mid 05.
Data and Graphics too
First there was ShortMessageService. It gained wide appeal and is still going strong in mid 2005. Uptake of the replacement WirelessApplicationProtocol (WAP) had not fared as well.
WAP is slow due to limited processor capability, which is in turn affected by energy consumption concerns. However the telecomms industry has refocussed their investment into cellular network infrastructure. After ThirdGeneration investment wave in late 90s, watch for BroadbandWirelessAccess to trigger a new boom.
The cellular system has advantage over satellites in cities due to line of sight limitations of the latter technology.
The future is with SmartPhone.
Roaming had been an issue with WiFi based MobileCommerce. Not with MobilePhone
Currently with a BlueTooth tri-band phone with GPRS (see GeneralPacketRadioService) (2.5G but 115Kb not too bad) and BlueTooth HandHeld or laptop you can go to most large cities in the world and surf the net/get email/vpn to work without being tied to a hotel room or spending all day trying to find a wired internet cafe which are even more scattered than hotspots. Most GSM/GPRS providers have roaming agreements however with WiFi even within your local city you have to have multiple accounts to use different provider's hotspots. There are free hotspots but the pay-per-use providers have much more coverage. Trying to use it abroad is even worse. However roaming argreements for WiFi are being forged and should be easier in the future. Websites exist showing general wireless access points for instance http://www.nakedwireless.ca/winudcol.htm (created from WarDriving?) including private APs where even WEP has not been turned on theoretically if dhcp is turned on (which it is by default) you could piggyback on a private network for free surfing but this is not legal or ethical.
See WikiPedia for information on what features are available, at http://en.wikipedia.org/wiki/Mobile_phone_features