Issue with EP user Ids

Dear All,

We have ECC6 Userids who perform ECC6 transactions through SAP-GUI and also access SAP-HR through SAP-EP (for ESS/MSS functionalities). SAP-EP has Logon-tickket based SSO with ECC6. How can we use the same user id for accessing ECC6 transactions through SAP-GUI.

For example:- In portal we are using P00161698 but in ECC6.0 we are using 161698. We want to use the same id:161698 for ECC6.0 as well as for portal.

So please let us know how we can use same user Ids in both server.(Portal and ECC)

Thanks & Regards,

Adarsh