No audio on encrypted calls (TLS/SRTP) with Yealink T54W firmware 96.87.0.15

[viktec]

Description

Calls are established correctly, but there is no audio (RTP) on internal↔external calls when a Yealink T54W uses encrypted signaling (SIP over TLS on 5061). Audio works when the same phone/account is configured in clear (SIP 5060). The issue appears related to a Yealink firmware change that introduces/forces SRTP ciphers not handled correctly by the phone unless a compatible cipher list is explicitly provisioned (NethVoice handles SRTP correctly).

Steps to reproduce

1. Provision/configure a Yealink T54W running firmware 96.87.0.15.
2. Configure the account to use encrypted signaling: SIP over TLS (5061) and SRTP enabled.
3. Place a call (internal↔external).
4. Observe that the call is connected but there is no audio.
5. Reconfigure the same phone/account to use clear SIP (5060) and place the same call again.
6. Observe that audio works normally.

Expected behavior

With TLS (5061) + SRTP enabled, calls have two-way audio.

Actual behavior

With TLS (5061) + SRTP enabled on Yealink T54W firmware 96.87.0.15, calls connect but have no audio.

See also:

• https://helpdesk.nethesis.it/a/tickets/196258
• https://helpdesk.nethesis.it/a/tickets/199454

# (template change): extend match to include T5 family

# Before
# Fix SRTP error
{% if provisioning_user_agent matches '/(SIP-(T3|T4|T7|T8))|(AX8)/' %}
account.{{ line }}.srtp.cipher_list = AES_CM_128_HMAC_SHA1_80,AES_CM_128_HMAC_SHA1_32
{% endif %}

# After
# Fix SRTP error
{% if provisioning_user_agent matches '/(SIP-(T3|T4|T5|T7|T8))|(AX8)/' %}
account.{{ line }}.srtp.cipher_list = AES_CM_128_HMAC_SHA1_80,AES_CM_128_HMAC_SHA1_32
{% endif %}

[Stell0]

1.6.6-testing.2