We purchased some Grandstream WP825 wireless phones to try to integrate with our CUCM 15.0 configuration. We've been running C7925 phones for years on older CUCM versions, and while we've had reasonably good luck with those, the audio quality just isn't up to standard now. Cisco's current WiFi phone options are quite expensive, so we felt like the WP825's would be a good alternative. The issue we're having is that these SIP phones don't like talking to our other Cisco SIP phones. Specifically, we have a few 8851 phones in the environment, and that's the direction we're moving. The WP825's work just fine with the 7925 wireless phones, or any older 7911, 7941, 7945, and 7965 phones we still have in our environment. They also work fine with Cisco's ATA191 SIP adapter. But for calls between the Grandstream phones and Cisco 8851 phones (both SIP devices), we have one-way audio. The party on the 8851 can hear the party on the Grandstream, but the reverse is not true. We've verified that the Grandstream is set to use compatible codecs, and the codec list in CUCM has lots of overlap. We even set the Grandstream phones to prefer G.722, which is what the 8851 devices show they're using. For some reason, we still only have one-way audio. Has anyone else run into this with either Grandstream or other 3rd party SIP phones on CUCM? If so, what did you do to resolve it? Any help would be appreciated.
