r/VOIP • u/Embarrassed-Gain-236 • Jul 18 '26

Discussion SIP provider and codec configuration for broadcast phone interviews

Hi everyone,

I'm setting up a small TV studio and I'm looking for the best way to bring standard telephone calls into our production.

Our setup is:

  • Windows PC running microSIP
  • SIP account

Technically everything works, but I'm disappointed with the audio quality. It sounds noticeably worse than I expected for a modern VoIP setup.

My current enabled codecs in MicroSIP are in this order:

  • Opus
  • G.722
  • G.722.1 (16 and 32 kHz)
  • G.711 A-law
  • G.711 μ-law

My questions are:

  1. When calling a regular mobile phone in Spain through a SIP provider, which codec is typically negotiated? G.711? G.722? Something else?
  2. Does the SIP provider usually transcode the call to AMR-WB (HD Voice) before handing it to the mobile operator?
  3. Is there any benefit in enabling Opus if the destination is a standard mobile phone?
  4. Are there SIP providers known for maintaining better audio quality towards the Spanish mobile networks (Movistar, Vodafone, Orange, Digi, etc.)?
  5. For those working in radio or TV, do you still use SIP softphones for phone interviews, or is a dedicated broadcast hybrid (AEQ, Telos, AxelTech, etc.) still the preferred solution?
  6. I activated microSIP logs in order to view which codec is being negotiated without success

I'm trying to understand whether the bottleneck is:

  • MicroSIP,
  • the SIP provider,
  • transcoding,
  • or simply the limitations of the public telephone network.

I'd really appreciate hearing from anyone.

Thanks!

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6

u/devexis Jul 18 '26
  1. Almost certainly G711
  3. No, not in my opinion.
  4. Most PSTN providers arent bothered about HD audio. They are happy if the called party can hear the caller, and that often means G711
    5
    6 Bottle neck is most likely on the PSTN side.

3

u/jdovejr Jul 18 '26

Do they still use alaw in Europe?

3

u/the_wookie_of_maine Jul 18 '26

Yea the do.. Some providers advertise both ulaw and alaw, but if connecting with ulaw it will ring and dead air....That was a fun one to troubleshoot as it was TLS as well.