Planet switch, snom 300 phones & trixbox. line dropping & voice quality problems. Cape Town

Hi all.
I am really a novice and require help, which I dont seem to be able to find in South Africa.We installed trixbox 3 years ago, and have had problems with it dropping calls ever since we installed it, this is my last try at solving the problem before we go back to a POTS system (very sad)

Problem
Dropped lines & noise on the lines

Hardware & software
10 x snom 300 phones version 7.3 software
PLANET FGSW-2612PVS
IP # are not fixed
the phones are in line with the PC
trixbox version 2.3.1.7
UTP cabling CAT 5
3 BRI lines 6 channels
the hunting is handled by the telkom company.

What we have tried.
After living with the problem of Dropped lines & noise on the lines for sometime, we decided to move away from trixbox (because of the lack of support in South Africa) and have a vendor install another solution.
The vendor installed a mypbx solution, simple fact the problem was even worse so we have moved back to trixbox.
We dont seem to be dropping any packets.
We have also tried disconnecting the BRI lines one at once and it seems as if we have the same problem across all the channels.
The service providor www.telkom.co.za tells us everything is working fine.

Questions
It seems as if the problem is the network?
Can it be the switch, and how do I test it?
Can it be the cabling, how do I test it?
Can the PC interfere with the quality of the call as they are inline with the phone. (cabling)
do I need to rewire the building from UTP to SIP cabling?
How do I check the planet for load (visual representation)
could the problem be the voltage on the POE lines, can I check it?

I have paid for a support package, but first we would like to eliminate the network & switch as the problem, as it will be difficult for a technician to monitor a network problem, if they are not on site.

If someone can give me a little pointer in the right direction I would really appreciate it.

regards
Darren

Hi Darren,

I hope I am not late in my response and you already moved back to POTS system…

Anyway, you might want to try PBXMate. This software package will help you to:

  1. Remove noises from the calls.
  2. Monitor the quality of the call and the network.

Regards,
Tim