Why can't I receive mms on my Curve 9300 from another smartphone apart from bb?

I cannot receive picture messages from another make of phone to my Curve 9300. I can send mms though. Says to download but won't download the pictures :-(

have you called your carrier?

MMS is a carrier issue, and not a part of BIS (BlackBerry Internet Service)

All rectification for MMS will come from your carrier