Alcatel H2P with Asterisk TLS media encryption one way audio problem

[Sudhakar]

We connected two Alcatel H2P Desk phones to Asterisk 18.19.0 with TLS 1.2 With Media Encryption SRTP

A party(Alcatel 1) B party( Alcatel 2)

A party --> calls to --> B party
Call is connected
Only one way audio is hearing -> Only B party hears A party voice
A party cannot hear B party voice

In the asterisk logs we are getting below error

SRTCP unprotect failed because of unable to perform desired validation

Could you help me?? Anybody faced the same issue and resolved?

Regards,
Sudhakar

[frank]

First, is the audio working without encryption on RTP?

[Sudhakar]

Hi Frank,

The Audio is working without encryption on RTP.

[frank]

can you share tcpdump traces , specifically around the SIP Negotiation?
I'm surprise the call is established if the SRTCP does not work from the beginning. it should fall back to RTP without encryption,
Run traces on both end and see who does what and who complains about what