Do not disturb details

i use my phone for zoom calls. I have automated the the do not disturb function to silence my incoming calls while in zoom. But It seems the DND function does not allow my customers to leave voicemails. I have 2 phones and have been experimenting different methods to the resolve this problem. It has worked once where I could leave a voicemail while my other phone was in a zoom meeting. But it’s inconsistent.