My name is Jordy, an Amsterdam Software FBO One Consultant.
Which number did you try to call?
We just tested our connection and we are available on both our Amsterdam phone number (Ries Vriend, CEO) (+31 20 620 56 97) and on our New York phone number (Marijn Beck, Country Manager USA) (+1 201 365 4408).
Should they both not be available then the phone service will send an email directly and they will call you back asap.
Ries and Marijn also quite regularly check their e-mail, so you should also be able to get in touch with them via e-mail.
Here you can find our information: Our Faces
Hope this helps!