My customers IT tech set up a VPN between their main location and a new location ten miles away. The customer has an NS700 with both digital and IP phones. The NT543 remote site phone works great with outbound calls and intercom to digital phones. When the remote phone calls another NT543 phone at the other location they only get one way audio. The customer has fiber to a warehouse and manufacturing building so NT phones were installed and working great.
Cisco routers and switches throughout.
Does anyone have a config like this working?

One way audio is always a router problem , I repeat always a router problem . Usually they do not have the correct ports open but some times it is the router itself .

Thanks rotary dial tommy,

When I got into this business, rotary was king. "push button" sets took them out like the IP phones are taking out the digital phones. Can I retire now?

any specific ports that I need to have the IT guy check? thanks again!

Try 405-407 plus many more but that may be wrong . If I don't write it down , I forget in 5 minutes I will check my notes .

We're on the same page - then I have to find what I wrote it down on. Thanks

We're on the same page - then I have to find what I wrote it down on. Thanks

The NT phones in the main office, were set up with static IP addresses and working without the need for the Gateway address for that site. The default gateway setting was 0.0.0.0 and the voice packets could not reach the vpn. Once the main office gateway address was programmed into the NT phones, the problem was cured...... Of course, this is after I told the IT guy that the problem had to be in his router. Any have a bite of crow for me : (