It sounds like you may have call forwarding active. There are two types; immediate and conditional. Immediate call forwarding will just take all calls and send them to another number. Conditional will route the call to another number after you don't answer or if you are already on the phone. It may be routing to the number 78 or *#3 because you may have dialed something in your pocket. Try dialing *73 from your phone to cancel all call forwarding and your voicemail should work again! Let us know if you need anything else!
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