Asterisk CLI shows that sounds are playing, but actually they're not

Okay, my setup is as follows:
I have an analogue phone connected to the Asterisk server as an extension. Also there’s a SIP client on my laptop.
FreePBX version 2.9.0.12 and Asterisk 1.8.10.1. They’re on a VPS server.

The problem is that neither of them play any sounds, eventhough while calling with the SIP client, it shows in the CLI, that it’s playing the sounds. Now, I’ve messed about with the audio codecs (as in, I’ve allowed gsm&alaw&ulaw), I’ve even added the necessary sound files to the right path, used chown since it threw some errors, but still no luck. In addition, the SIP extension says that it’s registered, but unreachable.
Also I’ve forwarded the necessary ports from my router (Thomson TG 789vn).

Any help would be greatly appreciated.

This sounds like it’s probably all audio and not just playing sound files. To check try echo test (*43) or call another extension. If that’s the case then probably a nat issue. Do you have nat=yes on the extension?