Audio quality issue with sip outbound call

[multib0t]

Bug Description

Hi I have an outbound agent using sip trunk in twilio. I noticed some audio quality issues with tts. Specifically I get sort of fading parts of the words ie missing / fading letters and the same agent config when i use as inbound call is working perfectly. I tried different sip trunk provider wavix but the issue is still there. I tried different tts ie openai, fishaudio, deepgram, elevelabs, cartesia and same is happening for all. is this a samplerate issue or hd codec not enable on cpaas provider? Any help would be appreciated.

Expected Behavior

I would like the sound to at least as good as for inbound

Reproduction Steps

initiate outbound call to my number

Operating System

mac linux

Models Used

No response

Package Versions

"livekit-agents[azure,deepgram,openai,silero,groq,cerebras,cartesia,elevenlabs,fishaudio]==1.2.18",
    "livekit-plugins-langchain>=1.1.6",
    "livekit-plugins-silero>=1.1.6",
    "livekit-plugins-noise-cancellation==0.2.5",

Session/Room/Call IDs

No response

Proposed Solution

Additional Context

No response

Screenshots and Recordings

No response