Connection using Linksys WRTP54G / Hardware Issue?

[snsd]

#1 I have successfully set up my FPL service using a WRTP54G combo ATA/Router. However, there is a rather loud hissing sound when on a call - more obvious from my end than the receiving end. I spoke with the incredibly helpful folks at tech support and all my setting seem to be fine. I'm wondering if anyone has any ideas as to what I might be able to do to get rid of the hissing. I have attached an image of my configuration file in case that helps. However, prior to delving into this, please read #2 below.

#2 I'm wondering if this is purely a hardware issue. When I hardwire my modem directly to my laptop or through a different router, I get a download speed in the 25MBps range. When I hardwire through my Linksys WRTP54G router/ATA, my download speed is in the 8MBps range - a 70% drop. I'm wondering if the router is simply faulty. Does it sound like I should simply get another ATA device or do you think I might be able to salvage it? (I can get a brand new LINKSYS Cisco PAP2T-NA for $35.)

#3 If it does NOT seem to be a hardware issue, the other challenge I'm having is connecting the ATA to my ASUS RT-N13U router. I seem to be only to get VoIP to work if I connect my modem to the ATA first and then the ATA to the wireless router. The correct way to to do it is to connect the modem to the router and then the ATA to the router. However, when I do it the "correct way", the router does not recognize the ATA. Again, I'm wondering if faulty hardware is the issue.

Any assistance would be greatly appreciated.

Thanks,

Dave

[Amowagou]

#2 You may have enabled the QoS of the router and hence restricting the download speed.
#3 Why do you want to connect your WRTP54G behind the ASUS?

I see that you did not enable the codec 711u, perhaps you should set it as the preferred codec and see if it helps.
Your router/ATA has two phone ports, you may also try using the second port as there may be hardware issue with the first port.
If you are using a cordless phone, replacing the battery may also help.

[dibsmft]

If you are used to using digital sound where there should be no carrier noise you may notice the "comfort sound" that your ATA is generating. If this is the case then you should turn this off under "Audio Configuration" under "Comfort Noise Generation". Without the comfort noise people often think they have been disconnected and ask "Can you hear me?" os "Are you still there?"