My company has a toshiba DK424 telephone system connected to a repartee voicemail system. The phones are a DKT2010-SD model. The problem is that on some extensions, when you call them, they are not getting through to voicemail. What will happen is that an extension will be dialed and the phone will ring but if no one picks up the system does not direct the caller to the person's voicemail. Instead a voice will come on and say that "I'll sorry but I didn't hear your selection please dial it again". Even through the person has his voicemail set up. This occurs only on some extensions. Is there any way to reprogram the phone to forward calls to voicemail after a certain number of rings? Any help on this will be appreciated.

Thanks!