I don't think there is a'trade in' facility on this Forum or a 'sales/wants' section. If you're asking if you can trade in your current phone for a new or 'better' one if the phone you're wanting does not come free with your new contract you can trade in your 'old' one in part exchange but, depending on the age, make, model and condition Vodafone will probably only give you around 25% or less than what it would be worth for you to sell it privateley or on an internet auction site. Trading in would have to take place in a Vodafone store. Also it might be worth noting to never sell your old phone to any of these Companies that advertise in the media, send for a bag, post it of and get ripped off, friend of mine sold one this way, was offered £120 for it, that was the quote, they said the phone was damaged, made a revised offer of £35 less £17 'handling and admin fees' so don't even consider that option!
Do some searching around to see what your old phone is actually worth by looking at the same model on auction sites, independent stores that sell PC 'S and phones will probably give you a better trade in price or you could just chuck it in the kitchen cupboard drawer as a spare and, if the one you want wasn't free on renewal of contract, pay the difference, the amount you'd have to pay will depend on the plan you'll be wanting. A phone's value will be better if you have all the original packaging and items that it came with when new.
