looks like the incorrect voicemail retreival number is programmed into your phone/sim card or voicemail may not be provisioned properly. can you enter your mailbox number and does it take you to your mailbox? if it doesn't then your voice mail needs to be re-provisioned by only a customer service rep can do this. while your on the phone with them, ask them to do a re-send to switch, it will push the proper retreival and deposit numbers to your sim card for the correct voicemail node your subscribed to.
hope this helps
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