SIP has no video or audio quality

Accuracy in the written word. Should I ask for less?

I hate it when people say “I read your blog about your phone selection”. It’s not a blog it’s a post.

I have even more people who mistake signaling for media. The issue at hand? A question I answered on Quora about SIP on smartphone operating systems. People simply don’t understand the simple concept:

SIP is a signaling protocol. It has nothing to do with the video or audio quality of the call itself.

Same goes for H.323. Or XMPP. Or even JSEP (that’s JavaScript signaling).

Quality of the media itself relies on a set of other specific technologies:

  • The codec itself – its characteristics, the specific implementation of it, etc.
  • The media engine – the way it handles and utilizes the codec, the way it sends and receives the media packets
  • The network conditions, and how both the codec and the media engine around it behave with it

That’s media.

And what does signaling affect?

  • The ability to actually dial a call and find someone to call to
  • The type of network and management that will be required (centralized, distributed, P2P, etc.)
  • Call setup times, responsiveness to user initiated control such as join conference, disconnect, etc.

Next time you try to understand if one signaling protocol is better than another or works better on one phone and not the next – take into consideration that signaling has nothing to do with it.

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  1. You missed out battery life. The signalling can have a huge impact on battery life, especially since a phone is only in a call for 2% of the time.

    • Tsahi Levent-Levi says:


      That is correct, but the question is – does batter life relates to media quality per se?

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