How often should let the phone ring before hanging up? Assuming that calls a person who knows he is in the office, he probably will answer between 1 and 5 phone rings. If the person is in a nearby office could be answering between 5 and 10 rings. Over 10 rings means recipient is not going to answer or is unable to do it, if you keep waiting is futile and also cause inconvenience to others who can not answer the phone. I do not understand how some people wait until the phone stops ringing and redial several times, incredible, if no answer and the first batch will not answer, should leave the hassle. If it is urgent, leave a voicemail if you can not do because the mailbox is full, it means that the phone you are calling is not handled correctly. So wait a reasonable time (not less than 10 minutes) and try again , use the email or cellular pager, even for the most daring can use social media to send more messages. But if no answer after 10 rings, what do you think is happening?