They typically don't care. Session Managers need an instance license for the server to exist. CM needs licenses for stations - whether analog/digital/H323/SIP.
Because a SIP phone is only useful on CM using CM features, the licensing is managed on CM.
So, when you buy a system new with 100 Aura Core users, it includes an entitlement for a CM phone, AAM mailbox, Presence Server account, etc,etc
It also gets priced to include 1 server instance license for the servers needed to fulfill that - so, 1 presence, 1 aam, 1 cm, etc
Build that phone as h323, SIP, digital, whatever.
There are exceptions like hotels adding gaggles of analog only ports for cheap or adding another CM instance because you want 2 PBXs for your users, but the overarching concept is paying for users and those users can connect from any type of endpoint - 9608 H323, 9608SIP, Windows softphones, iPhone, whatever.