Dan
You need to "port forward" your router, I could only find some info about the Telekom TSinus 130 here:
Port Forwarding for the Telekom T-Sinus 130 if this is your router then follow the instructions which will tell you how to configure (port forword) your router to use LW.
However, I also came across this as well:
Telkom premium combo ADSL wireless router security hole | Cape Town news
You may want to find out if there is a security patch available before you go any further.
UK Bob