Received a call after 11:00 PM, the caller left a voicemail.

As I was trying to check the voicemail the phone kept ringing five more times leaving 5 more voicemails in less than one minute. The voicemails are identical which means it is some automated dialin. A guy saying Hello, Hello at the beginning of the voicemail then followed my the sound of rain and water bubbling, waterfall sound.