AFAIK, active user are not available for calling.
so you need to go with named users.
if 35 user need multiple devices and voicemail, go with 35 professional.
Remaining devices based on the requirement you can choose enhanced or access.
If you are client, To design a proper solution I strongly recommend to involve a partner who is good in voice.
if you are a partner, contact partner support and they will help with BOQ.