I am trying to configure Linphone to wrap all media communications in an encryption layer (on Xubuntu). According to their website, Linphone supports:

Secure communications (TLS, SRTP, zRTP)

However, when I try to configure Linphone in Options > Prefs > Network Settings > Network protocol and select SIP (TLS) then Linphone immediately complains with the following error message:

Could not start tls transport on port 5060, maybe this port is already used.

Linphone works just fine when I switch back to SIP (UDP).

What is wrong and how can I fix it?

asked 12 Aug '14, 05:51

landroni's gravatar image

accept rate: 33%

edited 18 Aug '14, 15:43

I think I managed to figure out this one. In the end the issue doesn't seem to be on Linphone's side at all. It turns out that some SIP providers do NOT support transporting traffic through TLS (Iptel or Antisip), while others do support that: Linphone SIP service or Ostel.

To avoid the error above and to place a secure SIP call via TLS and using ZRTP encryption I had to do the following:

  • upgrade to Linphone 3.7.0: "possible to configure multiple proxy accounts with different transports (UDP, TCP, TLS)"
  • add a SIP account in Linphone using Linphone SIP service or Ostel SIP providers
  • for each account, in the SIP Account Configuration dialogue set Transport to TLS (instead of UDP)
  • in Options > Prefs > Network Settings set Media encryption type to ZRTP

Now you can check that all works as expected by calling the Ostel Echo testing service sip:9196@ostel.co and verifying that you see the message Secured by ZRTP - [auth token: ab34]. I suspect that the NSA should have a harder time intercepting that..


answered 18 Aug '14, 14:30

landroni's gravatar image

accept rate: 33%

I had the same problem and after lot of searching on the web, I didn't find any solution to it. I switched over to VoIPInvite SIP services and i am pretty happy with their services.


answered 04 Feb '15, 02:28

andolini7110's gravatar image

accept rate: 0%

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Asked: 12 Aug '14, 05:51

Seen: 20,454 times

Last updated: 04 Feb '15, 02:28

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