answered the phone,they hung up

called again and left no message.

Kept getting calls from this number for weeks at various times during the day.
Finally picked up the the phone to talk to someone called Steve who said he is organising a donation drive for Children affected by Leukemia.

They left no message, so I blocked them from bothering me with more than one ring in the future.

Phone rang twice.  When I picked up I got a dial tone.  I called the number back and got an automated message stated they were calling in reference to a campaign concerning research related to children's leukemia.  They gave a toll free number to call if someone is interested in obtaining further information.