Who called from 3233301465

Calls every couple of weeks, no message.  Who are these intruders?

No one spoke also when I answered.

I got a call from them, too

The number belongs to Americares.  They are an international disaster relief charity.  They are a reputable organization.

My called ID said Donor Services.  I have coantributed to Americares in the past so it may have beem that organization but I didn't bother and it only rang three times.