Orange free evening on net calls ??

[schematic]

Las night i did 453 on my phone and had the usual credit/texts remaining/photo msgs remaining but this time at the end i had 600 free evening on net calls, what are they and how do i use it? someone said to me it was orange to orange minutes, but it doesnt work.

[91mg11]

hey m8, i am on the offer

after 7.00pm until 11.59pm are free orange to orange calls!

[schematic]

ahh cheers, i was trying it after midnight...lol