The device in your purse or jeans that you think is a cellphone — guess again. It is a tracking device that happens to make calls. Let’s stop calling them phones. They are trackers.the New York Times
Receive voicemail anonymously, with SMS Privacy.
Most of the virtual numbers you can buy on SMS Privacy allow you to receive voicemail. This is particularly useful if the person you are trying to communicate with expects to be able to speak on the phone: if they can leave a voicemail it arouses less suspicion than if you can only receive SMS.
When calling a voicemail-capable SMS Privacy number, the caller is asked to leave a message, and then everything they say after that is recorded, up to a maximum length of 5 minutes.
In some cases it is possible to sign up for online services that verify your control of a phone number by getting them to leave a voicemail with the verification code. You then listen to the voicemail through the SMS Privacy website to receive the code.
If the service you're trying to sign up for does not provide verification codes via voice calls, you can buy a physical number instead, where the SMS will not be blocked.