OCS CAL std R2 IM and Presence
OCS CAL Ent Conferencing and Voice
OCS w14. Ent CAL spearated from Voice CAL
OCS w14 Ent cal Unified Conferencing
OCS w14 Voice CAL, Enterprise Voice
Is better to purchase the Enterprise CAL that include SA (Software Assurance) now in order to avoid paying for the additional CAl for voice.
If a clietn is already on ECAL then is good to go to face this challenge on licensing.