This problem comes and goes by itself without doing anything. Today the problem was noticed after a Cisco Call Manager shut down and reboot due to UPS maintenance.
Config of Voice Gateway attached.
IP phone to IP phone in same subnet 170.60.208.x/255.255.255.192 and between IP phone to IP phone in different subnets
170.60.208.x/255.255.255.192 and 170.60.209.x/255.255.255.192 all work fine.
But betwen PSTN phone and IP phone in subnet 170.60.209.x/255.255.255.192 there is one-way audio for about 10 phones. There are other phones in this very same subnet 170.60.209.x/255.255.255.192 that work fine.
Customer is not absolutely sure but he thinks all phones in subnet 170.60.208.x/255.255.255.192 are OK.
Pinging from the Voice Gateway to the IP phones that have one way audio problem works fine. No problem with pings. So there is no IP routing issue.
Could this be a bug in the version of IOS on the Voice Gateway. See attached SHOW TECH.