I have no idea; it's not exactly "popular" with the public either. But it's usually the only option that actually results in sorting out whatever it is you need to sort out. People aren't comfortable putting their personal details in email, so what's the alternative? Slow expensive postal correspondence?

This is probably a good place for me to link this excellent series of 3 posts on the operational politics and failures of the call centre concept: http://yorksranter.wordpress.com/category/callcentre/