Ext 49 is the limit with the small or large PC cards. Their are two manuals for the voicemail PC card, one version 1998 and one 2000, the 1998 leaves out a lot of detail, the 2000 update mentions the Extension 49 limit. If Ext 50 needs voicemail or direct transfer, then that user will have to be reassigned to a lower extension number. I have verified it with an ACS 7 system.