I have a DCS-816 Pone System with DS-5007S Phones. The issue that I Seem to have is that the voice of the other person on the phone is always very quite. I've turned the volume up on the phone witch when i put the handset down causes some feedback. Even with volume turned up to full the other person on the line is still very quite.

Has any one got any ideas? I think it might be the volume on the actual phone line. Is that possible?

I don't know if MMC805 is in a 816 but look at ATRK to DGP (analog trunk to digital phone) boost it

yea mmc805 works. I get two options,

TX Level Control > Level 0 - 1
TWS Gain Control > SLT - SLT: +0.0

Not sure what these mean and don't want to change them to i do.

Found out that mmc805's purpose is to Set the base level of TX volume and the TSW gain control for time-switch connect types.

I'm guessing I only need to change the TX Volume Level

As i'm new to these systems can any one tell me what happens when i change this option?

You need to take caution when making ANY changes in MMC 805. Usually changes made there are on recommendation from Samsung Tech support only. This is because the levels there do not just apply to trunks and can adversly affect other areas of the system. It says that your in the UK where I know the phone company lines are not as good as they are in the US. I would see if the phone company could do a decible level check on your lines first to see if it is low. If it is ask them to crank it up a notch. They can control the Db level on your lines there. Another option to prove it is not the Samsung system would be to hook up a regular phone directly on the line and see if you have the same problem. This would prove it to the phone company or the system. Let us know how you make out.