Asterisk certified/13.18-cert2 on Centos 7.
I have tested with multiple brands of hardware and software SIP phones, and conclusively determined that PITCH_SHIFT does not work when using a Linksys SPA9XX phone. I have tried the 941 (v 5.8.1 firmware), 942, and 962. None of these will echo a pitch-shifted voice back to me (I hear my voice without any shift), while my Grandstream GXV3275 as well as X-Lite and Zoiper are all modified correctly according to the PITCH_SHIFT setting. While I am competent with SIP and with Asterisk, this problem eludes me - and I really do need a resolution.
Does anyone care to take a whack at helping me diagnose this?