the first thing i would recommend is removing the sim card for a few seconds then put it back in and repower the phone. sometimes the phone gets stuck registered to a tower from another area you have been in. reseting the phones this way will reregister it with the proper tower. if that doesnt work then call tech support and and them troubleshoot the issue. worse case you may need to do a warranty exchange. i do know that cingular has had some voicemail issues as of late but that issue involved the feature not working properly on the account. hope this helps dookie. holla