Owning a mobile phone is not like owning a radio or a toaster. Payments to the network operator (which provides the mobile frequencies) cost around #163;200-300 a year - and that doesn’t include the cost of the calls.

The good news is that several companies hire mobile phones. What is more, they are keen to do business with schools and colleges. Complete Cellular Solutions for example, has set-up a hire service with teachers in mind. “We want to take away a lot of the worry teachers have when taking students out of schools, ” says general manager Pat Dunphey.

But anyone planning to use a mobile hire service should tread carefully, says Bob Tomalski, technical editor of What Cellphone: “Make sure the phone offers coverage in the area you’re planning to use it,” he warns.

There are four main mobile network operators, Cellnet, Vodafone, Orange and One-2-One. The first two offer the greatest coverage, although the others are catching up. Users should be aware that coverage is by population, not geographical area. Note also that halfway up a mountain, your mobile may be out of range of the nearest transmitter.

Mr Tomalski points out that battery life is important. “Don’t be fooled by the manufacturer’s figures,” he says. “Even the latest phones which claim to offer days of battery life can fall down on this promise.” The best mobile hire companies will supply a spare battery and charger, as well as an adaptor for running the mobile from a car battery.

Be sure to check the call charges, which can be confusing. Mobile calls are charged by the unit, which is around 24 seconds. But the number of units per minute will depend on the time of day you make a call. On average, a call from a mobile costs around 50-75p a minute (plus VAT).

If you want to use a mobile in continental Europe, you will need a digital GSM phone. Call charges for these are around #163;2 a minute. Some companies will even hire mobiles for use in the United States.

It is a good idea to take out insurance on the handset, although most policies carry an excess of around #163;150-200. Also check what accessories you get, and the delivery charge (most companies offer same-day delivery within the M25, 24-hours elsewhere).

Finally, if you’re worried about loaning a mobile to your students, only to find they’ve spent hours talking to their friends back home, relax. Many mobiles can be programmed with specific numbers (such as your school office) and will refuse to connect calls to others. Make sure you request this type of handset when you contact the company.

A USER’S GUIDE TO WHO HIRES WHAT * Adam Phones: Tel: 0800 123000 What they hire: Nokia, Ericsson. GSM also available Cost per week: #163;35 Call charges (approx): 75p per minute (peak),19p per minute (off peak) Delivery charge: #163;10 Accessories: two batteries and charger, in-car adaptor, leather case Insurance: #163;1.50 a day, Excess: #163;150 Other comments: shorter hire times available

* Carphone Warehouse Tel: 0181 896 5050 What they hire: handsets for UK, Europe and US Cost per day: around #163;35 Call charges (approx): 75p per minute Delivery charge: #163;12 within M25, #163;15 elsewhere Accessories: spare battery, charger, car adaptor available Insurance: #163;1 a day Excess: varies Other comments: delivery free if phone is collected from your nearest Carphone Warehouse

* Cellhire Tel: 0800 610610 What they hire: Ericsson, Nokia, Motorola. GSM and US available Cost per week: #163;39 Call charges (approx): 38-48p per minute Delivery charge: free Accessories: spare battery, car adaptor, charger, leather case Insurance: theft and loss protection, cost varies Excess: #163;200 Other comments: hire period can vary

* Complete Cellular Solutions Tel: 0171 234 0321 What they hire: Ericsson, Nokia. GSM available Cost per day: #163;35 Call charges: 75p a minute (peak)25p (off peak) Delivery charge: #163;5 (London)#163;10 elsewhere Accessories : spare battery, carry case, printed instructions for students Insurance: 50p a day. Excess: #163;100plus cost of calls Other comments: 24-hour helpline available