Changing a plan by either upgrading or downgrading is likely to attract a fee because this is considered to be breaking the contract. Consider the cost of the fee and paying out the existing contract against the cost of continuing with the contract before upgrading or downgrading.
The other issue with changing service providers is mobile number portability. The law guarantees that users can retain a mobile number when moving from one provider to another. So it's possible to change providers to get a better deal and keep the same phone number. However, companies may charge a fee to switch from prepaid to plan, or to terminate an account.
Making a decision about a phone isn't an easy choice with the vast array of handsets, features and functions on offer.
GSM - Global System for Mobile Communications is the world's most widely used mobile phone network and in Australia the network covers 95 per cent of the population. There's a plethora of GSM phones on the market from manufacturers including Nokia, Sony Ericsson, Samsung, Motorola LG, BenQ-Siemens, Sagem and Panasonic to name a few. Most new phones are quad-band GSM, which means they operate at 850/900/1800/1900MHz frequency and can therefore be used overseas on networks with frequencies different to Australia.
CDMA - Code Division Multiple Access is an alternative mobile phone network in Australia but it's only operated by Telstra. The CDMA network has more land coverage, particularly in rural and remote regions, but there are fewer call plans and a very limited choice of handsets. Telstra plans to shut off its CDMA network by 2008, replacing it with their new high-speed 3G Next-G network.
GPRS - General Packet Radio Service is a wireless communication service for sending data over the GSM network. This is what allows mobile phones to send and receive multimedia messages and email, browse and download files from the Internet. GPRS services have to be activated with the network and are generally charged per kilobyte of data.
PTT - Push to Talk allows a mobile phone to be used like a two-way radio. With the press of a button, rather than dialling a phone number, it's possible to speak to another person or group in a two-way broadcast conversation. The person or group talks back by using the same process with a compatible phone. Nokia and Samsung have released handsets with the PTT capability, but this technology hasn't really taken off.