Unable to call, listen to voicemail or see calls when abroad Non-EU

I am currently visiting the United States of America and have activated the voordeel 2000 aan, but i cannot place any call from my mobile phone as it is immediately disconnected. I am receiving messages that i have new voicemails but the phone immediately disconnected when i dial either 1233 or +31612001233. I have tried to download the voice mail app but it has declined saying the service is only available to people inside the Netherlands. I have even tried to forward my dutch line to my US one but i get an error message. I am stuck as i was expecting a call from a prospective employer. Kindly help