Ask HN: Help with this gateway configuration?

HN, I´ve tried saking on StackOverflow, googling for answers, looking at the API, but I have no idea how to make this configuration work.

This is my problem:

I have a gateway which has 31 chips inside. I have it configured so any incoming sms to those numbers are forwarded as a mail to 2 emails (clear in the image below). However the configuration makes it clear it can also do the opposite, it can make it so I can send a mail, and that mail be then sent as an sms through my gateway.

In short, I can do "sms -> mail", but haven't been able to do "mail -> sms".

This is the configuration panel for both things:

http://i.imgur.com/7dAQ5D2.png

This is the actual api/configuration manual for this model, which says nothing about the part I need: http://www.dinstar.com/uploads/soft/150630/DWG2000SerieslastestAPI.pdf

I´m out of ideas, is anyone able to help me as to exactly how this works? Does the gateway check my mail for messages with specific subjects? I have tried everything.

Thanks.