We were performing a new Elastix installation for a customer and made a discovery when working with some Yealink SIP-T20P handsets.
The Yealink SIP-T20P has a built in switch that provides a 10/100 bridged Ethernet port for connecting a end users computer. In our scenario the port was only providing limited speed... less than 10Mbps. The odd thing was that the phone and the switch were auto negotiating 100Mbps speeds.
This particular customer had a 100/20 Mbps internet connect with Comcast. When performing a speed test we were only recording 10Mbps speeds. With the computer connected directly to the network switch we were obtaining 80-100Mbps speeds to the internet without a hitch.
After troubleshooting we found that updating the phone to the latest firmware 220.127.116.11 from 18.104.22.168 resolved our issue.
I should also note that this is not a bug that Yealink identified in their release notes for 22.214.171.124.
We hope this post assists anyone else with similar issues.
Of course Safebit Solutions Inc. can always assist with your VoIP deployment.