I am getting calls from this number also. They stayed on the line long enough for a short vm recording and it sounded like a call center. I'm not answering or calling back if they are not going to leave a message.
They used to call me about every other week, reminding me that I can donate blood again & practically begging me to make an appointment. I understand that they are at a constant need for blood, but I don't need someone calling me ALL THE TIME to remind me. I will donate in my own free time whenever I want to.
Also, ever since I've stopped answering their calls, they have been calling me every day. Quite a bit annoying.