Connect Error
With firmware version x.73.x.x or higher, the Yealink Login is based on an Internet Explorer component. If the IP address of the Yealink phone is not in the security zones "Local intranet" or is "trusted", the HTTP connection to the phone may fail.
Therefore, make sure first that you can log on to the Yealink phone via Internet Explorer.
Action URI allow IP List
For Yealink phones the IP address of your computer must be entered in the "Action URI IP allow list". See: [Yealink-Web-Konfiguration > Features > Remote Control > Action URI allow IP List]. The entry should make TAPI driver automatically.
In the context of Asterisk TAPI driver there are still problems with the firmware x.73.xx The "Action URI IP allow list" must be set manually in this case via web browser.
If the "Action URI IP allow list" was set or changed first time, the next CTI/TAPI dial action must be confirmed once on the phone. Then also CTI functions such as "Answer" are executed by the phone.