EIC for HCM

Hi,

We are using HCM module of SAP ECC 6.0 & EP 7.0 for ESS

Our company planning to impliment EIC for HCM.

I have refered many document regarding EIC, bit confused.

CRM is neccesary for implimenating for EIC.

Can't we utilise ECC & EP for EIC implimentation

Appreciate for qucik reply.

Regards,

Anil Bhandary