If you are trying to connect up to your Raspberry Pi from an outside IP address (which if you are on the cellular network, you are on an external IP address) then you need to configure port forwarding on your router.
This allows you to use the address (for example) "http://me.example.com:9600/raspi" to connect to your raspberry pi.
You will need to add the raspberry pi IP address to your router configuration in addition to the port number (9600 in the example above) that you are using. Note that some linux implementations don't allow you to use a port less than 1000, so keep that in mind.
To find the IP number on your raspberry pi, type $ifconfig
and look under "eth0" if you are wired, and the wireless entry, if connected wirelessly.
A good description and tutorial on router port forwarding is