PITCH_SHIFT doesn't work with Linksys SPA9XX phones

Greetings all,

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?

Thank you!!

How are you testing?

Are you calling another person, Using the Echo() app, Using the Record() app and then playing back the recorded file?

Could it be the 941 has a lot of local sidetone?