Fifteen years ago, mobile phones were status symbols for businessmen, and objects of ridicule for the rest of us.

Today, they’re part of everyday life – as we do the bills, which might easily tip over £50 and which we reluctantly pay with a resolution that we’ll be a bit more careful next month. But around a third of us consider our mobile as our main telephone, so when that call needs to be made, we rarely think about the relatively high cost of doing so.

Of course, the big four UK operators – Vodafone, O2, Orange and T-Mobile – are perfectly happy. Their Government-granted licences to operate have, in the opinion of some industry watchers, created one of the most functional cartels in existence, with a marked disincentive to innovate or drive down prices for consumers.

That may be about to change. A new service, Blyk, is due to launch by the end of the summer. Running on the Orange network, it will offer completely free call-minutes and texts to its 16- to 24-year-old user base. In return, targeted advertising will appear on the handset. So are we being shortchanged? Exploited, even?

We’ve had these hopes before. In 2003, an additional licence for the most up-to-date kind of network, 3G, was granted to the phone company 3. Since then the company has portrayed itself as the enfant terrible of the mobile world, offering groundbreaking offers and new services before the big four. For example, a 3 deal offering 500 free minutes with a SonyEricsson phone costs just £15 a month, while you’d pay £20 more for a similar deal with Vodafone and get just 100 free texts in return. Years after 3 launched, we still haven’t got to grips with where our money goes. Time to make ourselves better acquainted.

1. UNUSED MINUTES

It used to be common for unused minutes, paid for as part of your monthly contract, to roll over until the next period. This is no longer the case. While there are exceptions – certain Orange price plans allow a roll-over for one month – few of us bother to check if the time we spend on the phone matches the time we’ve paid for. A recent survey conducted by Uswitch.com revealed that around £1.8bn worth of calls and texts included in monthly contracts go unused each year – that’s £90 per person. It’s no surprise that many of us are too lazy to keep tabs on our tariffs and talk-time. And the mobile networks aren’t about to remind us.

2. TEXT MESSAGES

The text message: a quick, simple method of communication, right? Perhaps, but also one of the most expensive. A 160-character text message – just 160 bytes of data – can cost around 12p to send to another UK mobile. Byte for byte, this works out to over 12 times what Nasa pays to retrieve data from the Hubble Space Telescope. With 4.5 billion messages sent by UK mobile users this May alone, and the number increasing all the time, there’s not much incentive for the networks to lower their prices. But there are some neat ways to work around the problem. For example, a company called Vyke (www.vyke.com) sells an application called Vyke Mobile Lite, which works, if you have one, via your phone’s internet connection to let you send texts to UK mobile phones for 2 cents (1p) each. This beats the cost of “free” text bundles – and doesn’t run out at the end of the month.

3. DATA CHARGES

With bigger, better screens and faster internet connections (a benefit of the 3G networks), cellphones are increasingly being used to surf the web and send email. But the differences in price between the networks is astounding – especially if you don’t set up an internet-specific package first.

Vodafone charges £1 a day for using the internet. But if you go over a 15Mb download limit in that day, you pay an extra £2 per Mb. O2’s “i-mode” service comes in at a hefty £3 per Mb of data. To give that some context, the front page of the BBC News website is around 350k – that’s a third of 1Mb.

Compare these charges to T-Mobile’s “web’n’walk” plan (£7.50 per month for “unlimited” use, which in practice means up to 1Gb – 1,000Mb – of downloads) or 3’s similar ”unlimited” and even cheaper deal (£5/month). It’s clear that being on the wrong network can multiply the cost of browsing by a factor of 600.

If you’re already stuck in a contract, you can still reduce your data bills by installing the Opera Mini browser, which compresses page sizes by between 70 and 90 per cent.

4. TERMINATION CHARGES

If you’ve ever wondered why you can spend hours talking to your loved ones on landlines for peanuts, but have to fork out eye-watering sums if you’re on a mobile, you need to know about termination charges. These are the fees levied when a call goes from one network to another. When a landline operator accepts a call on to its network, it charges less than a penny a minute, but the mobile firms have charged as much as 15p. On 1 April this year, the regulator, Oftel, cut these charges to under 6p/min for all five mobile networks. They have been given a year to phase in the changes, whose benefits may be most evident on landline bills.

5. TARIFF CONFUSION

With tens of thousands of different deals, the cellphone user can get lost in a sea of minutes, texts, cash-back and bundles.

Theoretically, the equation is simple: the more you pay as a fixed monthly charge, the less you pay for your calls. The reality, however, is far more complex. Sites such as Uswitch.com and Moneysupermarket.com can help you pick your way through the minefield, but you need to have an exact idea of your calling and texting habits.

Check the length of your contract. Some can tie you in for as long as 36 months – and don’t be too swayed by offers of free iPods and PlayStations. Steve Weller at Uswitch.com also recommends avoiding the high street stores.

“They’re on a commission, so they will try and get you on to a bigger package by telling you that you can change it after a couple of months. Which is true, but they’ll only let you upgrade up, rather than down. So it’s often better to go for the smaller package initially, even if you have to pay more for the handset.”

6. CALLING WHILE ABROAD

Mobile networks across the world have made enormous amounts of money from customerswho use their phones whileabroad. When the EC first started investigating over-charging within Europe back in 2000, they discovered per-minute chargesas high as €5 (£3.30). But roaming charges will finally be capped within the EU starting on 30 August: the cost of calling will be limited to 38p/min, and the cost of receiving a call to 19p/min.

3 has been at the forefront of price cuts. It had already substantially lowered the cost of using its sister networks, including those in Australia, Hong Kong, Ireland, Italy and Sweden, but then undercut even the EU recommendations by reducing the cost of calling to 25p/min throughout the EU, and 10p/min to receive calls from the UK.

7. CHANGING NETWORKS

Taking your existing number to a new network should be simple. It merely requires your old network to give you a porting authorisation code (PAC). But it can be difficult to persuade them that you really do want to leave. Be firm – but also note they are allowed to charge you up to £30 for the PAC. Once you have it, simply give it to your new provider. The changeover takes around five working days, but in Ireland it takes two hours. “The system,” says Steve Weller from Uswitch.com, “is slow, and Ofcom is trying to cut the time it takes to migrate. It’s in no one’s interests to hold up the process – companies may lose customers, but they’re gaining from their rivals because the market’s saturated.”

8. INTERNATIONAL CALLS

“The mobile phone market is the only one left where you’re forced to pay more money for calling internationally from the UK,” says Hjalmar Winbladh, CEO of Rebtel, whose service was launched for precisely this reason. “It’s 10 times cheaper for, say, Vodafone to connect a call to China Mobile, than it is for them to connect a call to the 3 network. But this isn’t reflected in the prices charged back to consumers.” While we wait for the networks to offer better deals, check out www.rebtel.com, which assigns UK numbers to your friends abroad, allowing you to call them as part of your free-minute bundles.

9. WEB CALLS

Using mobile handsets to talk for free via the is becoming more widespread. An application called Fring (www.fringcom) has a built-in VoIP (voice overinternet protocol) client that lets make calls on the Skype network via your phone’s 3G internet connection. The quality isn’t always tip-top, but it’sas cheap as chips. Some recent phones can also connect to wireless routers. This is a huge headache for themobile networks, as you can bypass them. Vodafone recently disabled the Wi-Fi capability of the N95, while T-Mobile has stopped connecting calls to customerswho were using its handsets Truphone, a VoIP provider. Truphone has won preliminary injunction against T-Mobile’s move, but this issue will run and run.

10. PAY AS YOU GO

The advantages of thisare obvious: you can’t landed with a unforeseen bill and you’re not in to a contract. But you may find yourself being hit hardest by the aforementioned issues. downloads can eat up your balance in seconds, you have no opportunity to upgrade,and some deals insist on a minimum top-up every month. “Many people aren’t aware that it’s possible to buy pay-as-you-go top-ups which act like – a number of free minutes, a number of free – which work out far cheaper than the normal rates,” says Steve Weller at Uswitchcom. With Orange’s Speak Easy Free Text Trigger, if you up by £10, you get 300 free texts the next month.