Whats a free sim pack and will they send me one?

im on VOdafone for my mobile phone, and the ad for the O2 free text for life thing came up, so i sent a text, and then sent a text back saying to send where you live, so i did that and they said theyll send out a free sim pack. do you think they will ? (note they also said it would take up to 2 weeks to arive) butwhat is a free sim pack?