O positive?

Desperately needed blood donors worldwide are being solicited by mobile alerts, according to GoMoNews.com. 

Israel's emergency blood bank asked mobile operator Cellcom to send an urgent SMS to all subscribers, asking them to donate.
Chennai India's campaign encouraged donors to sign up by texting their blood type to a designated code.

The Korean Red Cross has subscribers who agree to receive alerts when their blood type is especially needed.

The American Red Cross gives donors alerts when blood inventories are critically low or to announce special incentives for donating.