I tested with a softphone on my computer with obi110 disconnected and the muting is still there. I'm starting to think the problem is not in my equipment or setup. I'm going to give callcentric a try. I found this in depth explanation from DogFace05 on another forum, might explain what's happening:
"Bandwidth, jitter, latency, and CODECs have nothing, zip, zero, nada to do with half-duplex speech.
Half-duplex is caused by echo supression, which is just another fancy word for voice activated half-duplex. Echo supression and echo cancellation are two completely different technologies used for reducing echo.
Echo cancellation relies on very complex digital signal processing, requiring substantial amounts of computing power, that increases quadratically with the echo round trip delay. For this reason, it is only practical and only done at the near end, to reduce the echo caused by and sent back out by your equipment. It is never used to reduce echo produced by the remote end, as it would require far more computing power that is available to your ATA, and would also cause unacceptable speech latency.
The PSTN also do echo cancellation at the near end only, but due to the cost of the echo cancellation equipment, it's only done for long distance voice calls (it's usually automatically deactivated for fax/modem calls, as it would otherwise interfere with the proper operation of high speed faxes/modems). For local calls, the echo delays are so short that it's unnecessary.
Echo supression, on the other hand, is done to deal with longer delay echo, such as that returning from the remote end. It does nothing more than reduce the volume by some 30-40 dB of the inbound speech, anytime the adapter detects that you're talking (and for a slight delay thereafter). This is also the typical means by which low cost speaker phones deal with echo, as it requires virtually no computing power.
Because of the network latency between you and your provider, it makes little sense for them to try doing echo cancellation in their equipment. A competent provider would not do echo supression either, but it is altogether conceivable that some providers with little competence in designing a VoIP network and properly configuring subscribers' adapters, or providers dealing predominantly with BYOD customers, might take the easy way out and do echo supression to deal with their customers' echo problems, rather than doing things right."
