Unfortunately it is not possible to provision 2 accounts on the same phone with 3CX which would greatly help in setting the local SIP port so I'm trying to see if it is possible to get it working manually on my 3CX. In older Yealink firmware you could set a different local sip port per account on the accounts advanced tab. Yealink removed this option in the new firmware giving you only 1 option to set a local sip port for all accounts. This gives problems when I register 2 accounts on a Yealink phone to my 3CX. The phone does register both accounts on the same SIP port so it does not look like it is incrementing ports numbers. Is there a workaround or way to still get this working in 3CX?