The answering machine is a very powerful tool, you can exert different types of influence 
with it, or you can commit errors on the communication.
You can give a short call with your information and mention the purpose of your call.
If there is an issue where you had some e-mails going and coming back, you probably want to stop ping-pong messages that provokes a negative loop. You call, but you find the answering machine: give a large message with the strong approach you want to transmit and finish the message requesting to have a call as soon as possible.
There is people who prioritize the answering machine before the e-mail, there is people who do not take care about it (few people),so sometimes you will need to repeat the message via e-mail.
Take care giving so many messages, you will look like a jealous girlfriend.
Finally you can just hang up the telephone, and you will have nothing.
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