dunno. i do not like the idea of calling people listed on a website expecting them to take my call in a friendly way. hello, i saw your number on a website that you want to donate blood of O negative type. can you come to this hospital tomorrow? thank you?people add their details on websites at the spur of a moment. they might not have the same enthusiasm 10 days/weeks/months down the line. it would be just awkward. the service mentioned in the first post of the service looks more reasonable. send a sms to a mailing list and interested people can contact you back.