I'm in the same situation and customer support could not help me. They told me to go to a sprint service store. Please let me know how to fix this.
I'm having the very same issue.
phone support kept misunderstanding my problem as me just having issues setting up voicemail.
I'm having problems too, only after someone told me that they couldn't leave a voicemail. Every time I try calling my voicemail I get a busy signal. I have tried the *720 *730 and *740
Let's see if we can get your voicemail working again @runner6m.
Please check your inbox and get back to me when you have a chance.