[asterisk-users] Low RX volume and half duplex/"walkie-talkie" on AEX-804E

[Matt Riddell]

On 21/11/2008 6:47 a.m., Lincoln King-Cliby wrote:
> Hi All,
> 
> I have a ticket open with Digium, but based on their previous lack of support for the Asterisk Appliance, I'm not really holding my breath - and, honestly, I'm not 100% convinced it's a Digium issue in the first place (but I don't know where else to point fingers).
> 
> We have an AEX-804E (PCI Express, 4 FXO ports, Hardware Echo Cancellation) in a Dell PowerEdge 1950 with four straight analog telephone lines, and running asterisk 1.4.22. All of the local phones are Cisco 7961G with the SIP firmware. Calls between SIP sets, across our SIP trunk on a VPN to a remote office, or calls to or from the remote office's PSTN lines (over the aforementioned SIP trunk) are all fine.
> 
> On many [but not all] calls to or from the PSTN, I'm getting two complaints -
> #1 is low receive (i.e. from the PSTN) volume
> #2 (which seems to get significantly worse if I try tweaking bumping up the tx/rx gain in Zapata.conf) is that if the person in our office is talking all inbound audio is muted, but not the other way around (i.e. half duplex, but not half duplex both directions if that makes any sense)
> 
> Further compromising my sanity is that #1 seems hard for me to duplicate - calls to or from my cell phone, for example, always sound fine. Local calls are "mostly" fine, and long distance calls are hit-or-miss, calls to a Hawaiian (how's that for "Long Distance" from Ohio) 1004 Hz test number are fine - in fact, subjectively, borderline too loud which makes no sense since before going live with Asterisk, we had a legacy Panasonic KSU/PBX on the same lines - on the same punchdown blocks - and no one ever complained about these issues.
> 
> If I turn off the echo canceller there's a modest (may even just be psychological) improvement in line gain, but the echo is so horrendous (actually the echo sounds louder than the inbound call volume) as to make things unusable.
> 
> Any ideas? At all? I'm still relatively new to the Asterisk-interconnected-to-PSTN side of things, and it seems like there are dozens of config files and tools so explicit instructions are appreciated!

Try adding these to the modprobe line:

vpmnlptype=4 vpmnlpmaxsupp=11

-- 
Kind Regards,

Matt Riddell
Director
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