Call Disconnects on Yealink T26P

[ykpasupulati]

Dear Support,

Thank you for your reply.

Is this the version 70 which you are talking about on the website? What is the exact procedure for upgrading to this ?
The document talks about M1+M7 configuration files but there is no sample files anywhere to do it.

I have downloaded the firmware and put it in tftp server root folder but the phones are not picking it up.

Can you please let me know step by step procedure to upgrade to this firmware?

The issue we have is phones A receives calls externally from B and C. When they are on call with B if they receive call from C, A cannot hear B and they disconnect and C will continue to ring.

Regards,
Yogi