Hello Nguyen,
I have seen customers that have used the i.MX6Q for PBX systems, though unfortunately we do not have an app note or any documentation for you to guide in the development of a PBX system.
Indeed the i.MX6 is a good fit for it, the NEON processor helps a lot.
Have a great day,
Sergio
-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------