Please check that you have the correct type of routing selected:
1) Open the ActiveSMS Console
2) Select the 'Email' tab
3) Click 'Advanced Options...'
4) Select the 'Routing' tab
5) Select the option: 'To Address (e.g.
447710123456@smsgateway.com )
6) Click 'OK'
6) Click 'Apply'
Please note, you have created a non standard setup. You will only be able to send message to the one number. You would be better to use Subject based routing or use SMTP connectivity so that you can send messages to any number.