Solution : https://service.sap.com/sap/support/notes/651497 (SAP Service marketplace login required)
Key words : 
call function module rfc_ping, call returns successfully, wrong code page, correct code page, ascii code page 1100, communication code page, previously recommended workaround, -unicode system, reply appears, subsequent rfc
Related Notes : 
       
| 1319517 | Unicode Collection Note | 
| 1140770 | FAQ: F4-Help Cost Assignment | 
| 1084953 | Correct code page when receiving MDMP tables using RFC | 
| 745030 | MDMP - Unicode Interfaces: Solution Overview |