- Joined
- Jan 6, 2020
- Messages
- 56
- Reaction score
- 3
you are not running the correct firmware.
https://www.3cx.com/sip-phones/yealink-t1-series/#h.7ls0w5vyhlnd
Founded in 2005, when VoIP was an emerging technology, 3CX has gone on to establish itself as a global leader in business communications.