Whoever they are, they appear to have a series of numbers that they use, with the last digit changing. Always hang up after a small number of rings, never leave a message. They plainly want to sell me something. My phone is for my convenience, not theirs.

Missed a call from this number, called them back and got a message saying they work for non-profits.

Same as all above. Lots of calls - no msg left. Block & the last digits change. Just keep on blockin!!!

Keep receiving hang up calls from 9188 236X where last digit keeps changing as I block the previous ones... I think they are non-profit orgs looking for donations but never answer if they won't leave a message.

They never leave a message. How can I find out who this is??

They have been ringing me two to three times per week, and I simply refuse to answer. I have been curious to know their identity.

Phoned today. Left no message.