First, I would recommend using a "dummy" ACD queue in this instance, rather than opening up your voicemail system to potential fraud.
Program an ACD queue (LD23), putting the cellphone number in at the NCFW prompt and 1 in the MAXP prompt. You may need to put the ACOD of the route, if 9 + number doesn't work. Then use that for your zero out and remote notification for that one mailbox.
However, if you are certain you want to go the other way, check the NCOS and TGAR on your mail ports. (Not sure of the TNs? Go to LD 81 and type LST at the REQ prompt, then VMA at the FEAT prompt. It will list your Meridian Mail TNs.)