We can definitely assist you with this issue that you're experiencing with your voicemail. This was a known problem with Apple's iOS software version 12.2. To free up space for your voicemail box, please Access your voicemail by pressing and holding 1, then follow the prompts to completely erase the voicemail messages this way instead. This is simply a temporary work-around until you Update the software for your iPhone to the latest 12.3 iOS version. Let us know if this helps.
Sean, AT&T Community Specialist
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