Hey Mtroofer,
Sorry, I don't have any answers for you. I just wanted to add that I am having the SAME problem with my recently Jailbroken iPhone 4S with Absinthe 0.2 for Windows on my iPhone running 5.0.1 (9A405).
I posted in the Modmyi forum as well, but wanted to keep track of this thread to see if anyone had any suggestions.
In addition to the voicemail playback issue, I'm having two other issues as well:
1.) When I type on the keyboard, I don't hear any clicking sound. ("Keyboard Clicks" in settings is set to On)
2.) When I receive a new email, I don't get a sound. The phone vibrates, but no sound letting me know I have a new email. I do get these notification sounds for a new text or voice mail, just not one for new emails.
And of course the Voicemail issue. Here's what mine is doing -
When I play back voice mail messages, the sound only plays through my bottom speaker. I can't get it to play through the normal front mic (same one you listen to when on the phone). So I actually have to put the bottom of my phone up to my ear when playing back voice mails so I can hear them. The Speaker button on my voice mail screen doesn't change anything if I try to press it so it appears to be stuck.
All other sounds work fine (sounds during games, sounds during phone calls, speaker phone during phone calls, ipod, Siri sounds, etc...). My mute button is not switched on and I've made sure the settings appear correct for these sounds to play so I'm not sure what it could be.
Anyone have any idea what me and Mtrooper can do to correct the sound issues?
Thanks!!!