Blackberry offers to PAY iPhone users $600 to swap to its square Passport handset

It is billed as a tradeup - although many appear to disagree.

BlackBerry is offering to pay iPhone users up to $600 if they swap to its handsets.

The firm hopes to boost sales of its bizarre square Passport phone with its new promotion in what many see as a last ditch attempt for survival.

'Upgrade to a BlackBerry Passport and get up to $400 back for your iPhone and an additional $200 from BlackBerry,' the firm says.

The trade-up value is based on the trade-in value of your used iPhone and the top-up value paid by BlackBerry, it said - and stressed that iPhones must be working models.

In an FAQ posted on its site, the firm admits it will then sell the iPhones.

'Once your iPhone is received by Clover Wireless, it will be tested and inspected,' it states.

'The devices that are reusable may be resold to retailers, wholesalers or consumers.'  

After being unveiled at an event in June, chief executive John Chen has been teasing the square phone's features ever since - but it is believed sales have been poor.