What is the mysterious Centro plugged slot?

On the back of my Centro on the opposite side as my stylus, there is a slot that is plugged with a piece of rubber. I know that one could easily remove the rubber plug. Does anyone know what is behind it? There is nothing about it in the manual.

 

It is the connection for the cellular antennae if I am not mistaken. nothing that is consumer useable.

 

It's a plug for an external cellular antenna. Most phones have one.

 

That is exactly what I thought. Anyone try an external antenna? I do not get reception in the mountains where I live. I have heard that in some cases an antenna can help. Any thoughts?

 

It depends a lot on the terrain and how far you are from coverage. A small indoor antenna probably won't gain you a lot. But a larger antenna, or even a powered amplifier, can seriously increase your range.