I didn't know you could still get them! I had one years ago from work, we had to pay an annual contract for it then I think it was so much per message, because you couldn't send a message yourself, you had to ring a central number and they sent the message to the pager. It may be different these days!
No sure though, why does he need to contact you? - we never take our mobiles out when we go shopping, wouldn't even think about it.