[Q] No incoming call rings on i9192 Duos topic

I use a i9192, with 2 SIMs:
SIM1 is GSM, voice only.
SIM2 is dual mode (WCDMA-GSM), data unlimited (and data only, no voice service) and often sharing as a wifi hot-spot

SIM1 never rings on incoming calls. The calls go straigth to the answering machine.
SIM1 can do outgoing calls.

Can anybody help me receive calls ?