According to the offer page, you can claim your free “Nokia Purity Headphones by Monster” worth up to £199, on purchase of any Lumia phone (Even 610) in UK. What you need to do is,

  1. Enter your mobile number on the offer page.
  2. Throughout June, buy a Lumia 610 or 710 to get a pair of in-ear headphones or buy a Lumia 800 or 900 to get a pair of on-ear headphones.
  3. Text ‘nokiamonster’ to 64446 from your new Lumia.
  4. Choose your headphone colour.
  5. We’ll then send your fantastic free Monster® headphones.

This offer is available till the stock lasts. Till the time of writing, only 1640 were left.

Monster-offer page