How to amplify the network signal on the phone?

There is a trip to the wilderness mountains, where communication catches extremely poorly. But in some places she catches a little. I remembered that on the last phone there was a connector that is designed to connect an external GSM antenna. I looked at my current one and, unfortunately, I did not find such a connector, but 5 contacts of an unknown purpose were found, which are closed on a metal cover. What the hell are they for? And can they be used to amplify the signal? If so, how?