To begin with, make sure that SIM card, which you have inserted in RUT955 can indeed send SMS messages (i.e. that SIM card has enough balance to send SMS). Best way to do that is to try inserting this SIM card in any mobile phone and trying to send SMS message from it.
If you will be able to send SMS message from this SIM card (from any other device), but RUT955 will still show "Timeout" message, try sending SMS message one more time (to get timeout error). Then download troubleshoot package from "System -> Administration -> Troubleshoot" menu and send it to me via private message.