How does the U1900 interwork with a third-party phone?
701. Run the config softargu type 286 value 0 command to set software parameter 286 to 0 on the U1900 so that a third-party phone can register with the U1900.
2. Set the SIP server address to the IP address of the U1900 unified gateway on the third-party phone according to the authentication mode of the third-party phone.