When voicemail pins - or auto attendant options - are entered, they make use of tones generated by your handset.

Please note that 4HA accepts RFC2833 'SIP-INFO Signalling' (it does not accept in-audio DTMF signalling, as, for example, 3CX uses).  This may require a review of handset settings accordingly.

Please also refer to Common 4HA Device Settings.