We have a Nortel phone system at my office. T7316E The agent that set up the voicemail has left the agency and we do not know the code to change voicemail. Is there a way of changing it without the old code or how do we just delete the whole voice mail system? Thanks for your help. I'm not sure what number is the model no. NT8B27 AAAE6 N0074339 T7316E Rel 03 NNTMHPG26VNF