Sometimes there is a configuration issue or other conflict that can be difficult to resolve. In these cases it might be recommended to go back to a known good configuration. This can be accomplished by a factory reset. After a factory reset, the phones will automatically recover their programming (excepting any user made settings such as ring tones or speed dials). If a factory reset does not resolve the issue, it can be a way of proving a network fault.
Factory resetting a Yealink phone is a simple procedure:
If the reason for your reboot is related to difficulty in updating your configuration, this step should resolve the issue.
Yealink SIP-T19 & SIP-T21P-E2, Yealink SIP-T3 Series, Yealink SIP-T4 Series, Yealink SIP-T5 Series, Yealink CP860 (EOL), Yealink CP9 Series Conference Phones