How to cut the cost of your mobile phone Haggle for a cheaper deal Once you know what you are using, contact your network to see if they can offer a better deal. If you are still unsatisfied, it is worth considering switching providers to take advantage of competitive new customer deals on offer. Those who have been with a network for more than three months and are not using their full call and text allowance may be able to have a downgrade to a lower monthly tariff. The same is true if you regularly exceed your bundle's allowance of free minutes and texts and incur extra charges. Phone your provider's customer services department for a tariff check-up every three months, where they will review your bills and may be able to recommend something cheaper. But switching is easier than you think and you can even keep your existing phone number if you ask for a porting authorisation code (PAC) code when you close your account. This code allows you to transfer your existing mobile phone number from one network provider to another. Find the cheapest iPhone deal If you are looking for an upgrade to an iPhone 5, the cheapest deal currently available is from O2, according to uSwitch.com. This costs £26 a month for a two-year contract. The deal includes unlimited minutes, unlimited texts, 1GB of data, although it does come with a £249 upfront cost for the new iPhone 5 16GB handset. For a free handset, the tariff increases to £46 a month. Those who don't want a two-year deal should consider Vodafone, which is charging £51 a month for a one-year contract. For this you get 1,200 minutes, unlimited texts and 1GB of data, however this deal requires an upfront payment of £169 for the handset. Get paid for your old handset Another way to cut costs is to trade in your old phone. To check your earnings potential, visit sites such as O2recycle.co.uk, Mazumamobile.com or Mopay.co.uk. For instance, this week at O2recycle.co.uk you can sell your working Apple iPhone 4 (16Gb) for £141. It is even offering £126.90 for a iPhone handset with significant cosmetic damage. But bear in mind that you do not have to have the latest handset to cash in. For instance, an iPhone 3GS (16Gb), which was released in 2009, still has value. Type in the 15-digit IMEI number found on the back of the handset, send off the phone, and its value will be paid to you by BACS or cheque. Although the cost of phones changes regularly, most sites have a price promise, which means they will hold the one you see on screen for up to 14 days. In general, the longer you leave it, the lower in value a handset will become so it pays to be ruthless and recycle fast. Stop paying for 0870 calls Stop paying more than you need on customer service lines with the 0870 app for your smartphone. Many companies will use 0870, 0800 or 0845 for customer service, which can cost as much as 50p per minute to call. Free to download, this app will turn these numbers into 01 or 02 numbers, which will come out of your contracted minutes. If you do not have a smartphone, visit the company's website www.saynoto0870.com, which has a search engine to find alternative, and often free, numbers for companies. All you do is click search to find an alternative number and enter either the number or the company name. Save money on directory inquiries Often, the charges for calling directory inquiry services rise when you call from a mobile phone. Calls from an Orange phone cost 89p to its preferred number, for example This is a one-off charge, no matter how long your search takes. However, if you request a number by text it will cost you £1 to have it texted back to you. At Vodafone if you use the preferred number, you will pay 89p a minute. Use other 118 services, however, and getting a number could cost you up to £3 a minute so it pays to research the cheapest way from your mobile phone network. If you have all-you-can-eat data on your phone, you should consider using mobile internet to get a number, since this way you will not be charged. www.118.com and www.thephonebook.bt.com both provide numbers for free and you do not need to register.