"Twitter user @duvi found a workaround that will allow iOS users to download and install BBM even if they're not living in New Zealand or another territory that has been given access so far."
- as mention in Softpedia Article.
To do that you will need to change your Apple ID.You can do that by follow this simple steps:
- Open your App Store and scroll down the bottom of the page where
your Apple ID can be accessed. It's on the bottom left of your App Store. Click
on Apple ID and choose View Apple ID.
- Choose Country/Region and the select New Zealand as your country. After you clicking
Next you will need to fill in your personal information.
- First of all make sure you choose None in the Credit Card window, as your credit card
will not work in New Zealand.
- Under the Billing Address you will need to use a local address, so add in Jacksonville
under "Subburb" and 6004 as "Postal Code." - That's it! Search for BBM for iOS and you
will now be able to install it on your iPhone.
Duvi tested the workaround himself and it works. Enjoy!
Source :- Softpedia