abroad with local sim: can't access voicemail with my Verizon Samsung S5

[t2sa]

Hello there,
I'm currently abroad using an unlocked Verizon Samsung S5 phone and I bought a local simcard. The phone is working perfectly except that I can't have access to my voicemail. When I'm calling the number, I get the following message: "Connection problem or invalid MMI code". Is there a way around?
Many thanks...