Hello Susan,
From what I understand your husband works for Ericsson and he has a work mobile phone. I suppose because of the redirects you don’t feel comfortable sharing personal stuff over the phone. Have you tried calling him directly on his MO cell phone? I believe that calling the VoIP first saves you money (if the VoIP number is a local number for you).
So I’m not sure what you’d like to know, but to me this doesn’t seem so complicated: you call a landline that redirects to a mobile number. The mobile number, even if it is a US number can be answered anywhere in the world if there’s a roaming plan activated.