Before I start, this is a sort of guide for people wanting to buy a mobile but are unsure on what network to choose. It is under Vodafone because there is nowhere else to put it. Sorry if this is confusing!

Firstly, decide on how frequently and at what time of the day you are most likely to use your phone.

Then decide why you want a mobile, or if you actually need one. Would you be better off using a phonebooth in emergencies?

Have a look at all the FOUR networks, and the TWO airtime providers:

Vodafone

One to One

Orange

BT Cellnet

Virgin Mobile (airtime provider)

Plus Telecom (airtime provider)

Don't worry if you do not know what the difference between a network and an airtime provider is, there are basically no differences noticeable to the consumer. One difference you may notice is that Virgin and Plus Telecom do not offer as good a coverage as the other four networks, although this is really a petty detail. Also, Virgin top up cards are only available from Our Price (as far as I know anyway).

Look at their priceplans. Are you a heavy user of a mobile, a weekend and off peak user or an emergency user.
If you have answered heavy or frequent, you will most likely be better off on a monthly subscription contratct. These contracts start from about £9.99 a month going up to £49.99 a month for non stop users. They offer much lower call charges than on Pay as you Go. Also, phones are often offered for free on contract, however you are then stuck with the same phone and contract for a year. Contracts expire 1 year from the commencing date in 99% of cases, and you cannot cancel it before this time. Some contracts also have what is called a 'connection fee', which is usually about £30-£35. This is really an excuse to get more money out of you, and the networks claim it is for all the hassle of adding you to their system. Most contracts come with 'free' connection, however this is simply added to your line rental! Remember the old saying, 'there's no such thing as free' - unless you check out a site like www.ukfreebies.co.uk! Enough about that though, and back to the phones. One last thing, once your contract is up (usually after a year) you can do as you wish with the phone you received, including putting a pay as you go SIM card in! If you do not know what a SIM card is, read on to find out.

If you answered emergency user, I would recommend Pay as you go. This is also ideal for teenagers who cannot pay monthly subscription fees.
Pay as you go works by you adding money to your account as and when you need it, as often as you like. Call charges however are generally more expensive than on contracts, although you do not have to keep to an agreement and you are free to use your mobile as often as you like.
Pay as you go phones start from around £30, up to about £150. If you want a £30 mobile, hurry as all the networks are about to dramatically increase their handset prices. This is because many people never use their phones, and often resell them abroad for a much higher price. Also because the networks subsidise much of the cost of a phone, they never receive their money back.

Text messaging is available on any network and priceplan. If you want a phone purely for text messaging go for a £29.99 pay as you go phone. Messages cost pretty much the same on any network. Vodafone are the most expensive though.

There are too many priceplans on contract to list, so I will just consider the pay as you go tariffs for each network. All prices are per minute, and peak hours are roughly 8am - 7.30pm on each network.
Off peak hours are cheaper, and peak hours more expensive to make calls in, but not to send messages in. The text messaging tariff remains the same throughout the day.
Messages are around 10p each on all the networks, but vary above and below this figure slightly.

Voicemail is a service offered by all networks, in which when you are unable to take a call the caller gets directed to your personal answermachine, in which he or she can leave a message. You can then retrieve this message at anytime. Most networks charge for this service, however I do know one to one offer it for free.

Vodafone are the UK's number 1 network, and offer the best coverage. They are fairly expensive, however you have the reassurance of a good reputation. Vodafone currently offer a tariff of 25p for the first 3 minutes of each day and 5p after that on pay as you go.

One 2 One are an excellent pay as you go network, with a popular priceplan of 30p for the first two mites of every day and 5p a minute after that. Text messaging is pretty cheap too, 8p in most cases.

Orange are good for pay as you go also, and offer 5 free text messages a day. Priceplans vary, I was recently on 30p for peak calls and 5p on off peak hours.

BT Cellnet offer free calls to your favourite number, however prices of calls are fairly expensive. BT have a terrible customer service reputation too. (some of you may remember 'we can work it out' in which BT Cellnet was regularly slammed)

Virgin are newcomers in the world of mobile phones, and offer some great deals on pay as you go. Virgin also offer some decent phones at reasonable prices. However, similarly to Plus Telecom few people are on these networks yet, and so calling your friends on other networks will be expensive.

Also available are 'all in one packages', and these are rather similar to the contract packages. However, instead of paying monthly for your calls and line rental, you simply make a one off payment and you receive everything you need for your next year. This includes the phone, connection to your network, 12 months line rental and usually a certain amount of calls per month.
For example, Vodafone offer the Nokia 3310 on an all in one package, for £159.99 with a choice of free monthly calls. The choices are 500 off peak minutes, 60 peak minutes with low call charges, or 150 peak minutes. REMEMBER, all in one packages only give you a certain call allowance each month, and any surplus calls to this are chargeable.
The all in one packages are most suitable for low end users and emergency users of mobile phones.
Some networks even let you carry over any unused talktime from the previous month to the next! (I am aware Vodafone definitely do this at the moment, any other networks doing this le me know!)

Anybody that is sure of exactly of what he or she wants with a network, and wants a good phone to accompany this may consider purchasing an off-line mobile. An off line mobile phone is a phone not connected to any specific network or tariff, and is just the phone in the box and nothing else. A SIM card will be needed to make these phones work, and these are readily available for under £10 from any good phone store. If you don't know what a SIM card is, it stands for Subscriber Identification Module. SIM cards slot into your phone, and hold all your call details and some text messages. A phone will not function without a SIM card.
These phones are very expensive, and should only be purchased when you intend it to be used with a pay as you go SIM card. There is no point purchasing an off line phone, if you intend to take up a contract, as contracts always come with phones anyway!
As pay as you go phones are expensive, and as you do not always receive a good phone on it, off line phones are excellent with a pay as you go SIM card in them.
For a decent off line phone, be prepared to shell out a few hundred quid though. Most decent off line phones are unavailable on pay as you go usually.

If you would like details on any specific handset, e-mail me at pjm123uk@hotmail.com as I am quite up to date on handsets, and have more or less any handsets details at hand. (the modern handsets anyway)

Pagers are also a decent way to keep in touch, these are a lot cheaper than mobile phones, although do not offer all the features mobiles can offer.

Any suggestions on how I can improve this opinion, or anything I can add to it let me know and I'll do my best to do it as quickly as possible. :-)

Thanks for reading, if you've got this far (without scrolling!) You should be reasonably well informed. (I hope anyway!)