In an ideal world, there should be a sensible meeting of people where standards are designed and implemented internationally.However the world is not ideal as we know it, and mobile technology was no exception.
Back in the analogue days, US first came up with AMPS, a simple FDMA (refer to part 1 in case you are getting lost here) system on 800MHz FM band; Japan and the UK was soon to follow suit, however because of regulatory limitations they had to use a different variety on the 900MHz band. Continental Europe, however, went into a frenzy of devising their own national standards, none of which turned out to be satisfactory or economically viable after a few years.
Learning from their blunders, European telcos decided to poll their effort together to create a common standard. The collaboration was initially named Groupe Spécial Mobile, however the acronym GSM soon conflated with the term Global System for Mobile. GSM was designed from the drawing pad to be fully digital, modular, and capable of operating on several different frequency bands to suit national regulations. One major point that had to be mentioned separately is the invention of the SIM card, which allows the user to move his number from one phone to another with ease.
People of the present age often take SIM cards for granted, and indeed in New Zealand over 70% of mobile subscribers are using a prepaid SIM. Nonetheless, SIM card is actually a more recent invention. Back in the days when telecommunication was though to be of natural monopoly and AT&T decided what colour is your phone going to be, it is no big surprise that phones are sold hard-wired to a certain network. In Europe, however, many countries have laws in place prohibiting blatant bundling of service with a product. With the technology standardised between countries, there is no longer any excuse to lock users in. SIM cards also allowed people to change their phones more frequently so the manufacturers are actually quite happy with it.
Hence two very different business models developed on two shores of the Atlantic: American carriers grant heavy subsidy for handsets, often offering them free of charge to lure customers into signing a lucrative contract; even GSM phones are often sold locked to a specific network, even after the initial contract has expired. In Europe, most SIM cards are prepaid and carrier locks are virtually unheard of until, you guessed right, until Steve Jobs decided to shove the American way of life down everyone's throat.
Back then when GSM was rapidly expanding, AMPS evolved very slowly. The IS-54 standard made the internal handling of calls digital to triple cell capacity, while remaining compatible to the older standard externally for a smooth transition. The subsequent IS-136 standard is fully digital, however it came too late and GSM became the effective global standard.
The future of the AMPS family was sealed when a domestic foe appeared. A start-up company in California called Qualcomm pushed digigently for their radically different and innovative CDMA technology. Unlike GSM or AMPS, CDMA does not require a frequency switch during a handover process, resulting in a much "softer" transfer that nearly always goes unnoticed and rarely dropped. While GSM and AMPS are both subject to the limitations of TDM encoding, GSM was being continually developed to minimise any issue but AMPS lacked the momentum, not to mention it was not designed to handle frequent handoffs in the first place. Two major carriers, namely Sprint and Verizon Wireless, embraced CDMA because SIM card (correct term for CDMA is actually is RIM) is not mandatory, allowing the contract-based status quo.
Subsequently AMPS went into a slow but steady decline; service has been stopped in most countries by 2006. To this date only a few networks remain, all of which are in remote regions where the upgrade cost is prohibitive.
The same pattern of change played out in most parts of the world except in Japan, where the AMPS system was simplified to become PDC, which is specialised for the higher user density found in Japan. Because PDC allowed handsets to have lower transmission power, tiny handsets unimaginable elsewhere can be made. Manufacturers became obsessed with making even smaller units, culminating in the PHS system where all cells are microcells covering a radius of less than a kilometer. The domestic market flourished, while the PHS system was exported to gain a huge following in large cities like Taipei and Rio. Notwithstanding their relative success, the Japanese mobile industry became disconnected with the rest of the world for years, overlapping much of the lost decade.
In this chapter above I tried to summarise the development from 1G (analogue voice) to 2G (digital voice), the next chapter will devoted to the entire 3G fiasco of which the effects are still being felt today.