I have this setup.
PSTN -> SPA3102 (A) -> router -> cable modem -> internet <- dsl modem <- SPA3102 (B) <- PSTN
1. From A's Line 1 I call B's Line 1. I hear the person at B pretty well. B, on the other hand has a mixed experience - sometimes he hears me clearly, sometimes my voice is choppy. When I talk to B I can hear a faint echo.
2. From A's Line 1 I call B's PSTN line. The PSTN's (at B) dial tone is very faint it's almost inaudible except if you press your ears hard against the handset. The voice level at both sides A and the person at B's PSTN is also faint both ways. It's worse when I do (A PSTN to B PSTN to PSTN number).
Am aware of the FXS Input/Output Gain on the Regional tab and and the SPA-PSTN/PSTN-SPA gain settings on the PSTN tab. My question is:
a.) Will any of these have any effect on the dial tone volume in a VOIP-PSTN gateway call (at B) considering that the dial tone I'm hearing is a simulated one and not really the one that's coming from the PSTN?
b.) With regard to the communication volume in #2 above, which SPA needs to be adjusted since both are involved in the same communication?
c.) Besides the above-mentioned gain settings, what other settings influence the dial tone and communication volume levels?
d.) How do I reduce choppy-ness in the audio?
e.) Is there a better way to do this besides trial and error? I.e., is there a more deterministic method/software I can use to trim settings given known measurements, such as bandwidth, actual and perceived audio levels, etc?