Frequently Asked Questions

Linphone on mobile phones (Android, iPhone)

  • Q: What should I put in username and domain in the settings ?
    • In order to use Linphone to call any number, you need to subscribe a SIP VoIP account to a VoIP operator. Linphone.org does not recommend an operator in particular, however for convenience you can run the wizzard to create a free linphone.org account, which allows you to call friends also registered on linphone.org.
  • Q: Why H264 and MPEG4 are not available in Android and iOS versions available from Google Play and AppStore ?
    • H264 and MPEG4 are video encoding formats subjects to patents royalties, thus can hardly be distributed in a free application. We encourage people to move to VP8, which provides quality similar to H264, but is royalty free.
      H264 and MPEG4 support remains in the source code, so anyone building the Linphone application from source will get them enabled by default.
  • Q: Why SIP/TLS and SRTP are not available in Android and iOS versions available from Google Play and AppStore ?
    • Due to new restrictions in Google Play and Appstore policy for application submissions, we have been constrained to temporary remove all encryption features from the published applications. Re-enabling them requires getting authorization from US and France government agencies, which might take some time.
      However these features are not removed from source code and are enabled by default when building Linphone from source code.
  • Q: It works great with wifi but not in 3G ! Why ?
    • It is likely because your mobile operator is blocking VoIP traffic, because it forbids VoIP in its contracts.
  • Q: Why aren't you developing a VoIP anti blocage solution ?
    • Yes VoIP blocage is something that should not exist, that's not real internet. Technically, an anti-blocage solution requires a server infrastructure that linphone.org cannot afford, and we don't want to fight against anybody. Also, there are operators that don't block VoIP in many countries.

General questions

  • Q: Where can I have a ~/.linphonerc config file ?
    • A: You don't need a ~/.linphonerc config file: linphonec automatically creates one during the first startup. There are commands within linphonec to set various parameters. Only a few ones will require to modify manually the config file.
  • Q: Is there any windows port of linphone ?
    • A: Yes, windows XP is totally supported since october 2008.
  • Q: I have many compilation errors when cross-compiling for ARM-linux !
    • A: Cross compilation is not easy: follow the instructions given in the README.arm within linphone's source.
  • Q: I have audio problems during calls, what can I do ?
    • A: Especially on ARM-linux or old versions of linux, the audio devices are often managed with OSS drivers. Linphone, because it uses full-duplex audio and needs low-latency I/O, doesn't work very well with OSS drivers. You should prefer using ALSA drivers and choose the ALSA default device from the Sound Tab of the property box or using the 'soundcard' command of linphonec.
  • Q: Does linphone work behind firewalls ? What are the ports used ?
    • A: Yes it works in most cases. The simplest way to achieve this is to active STUN support from the configuration box. You 'll need to enter the name of a STUN server, for example stunserver.org. If your firewall or gateway does UDP masquerading, it should work without problem.
      You may want to restrict the open ports on the firewall: you need at least to preserve the SIP port (udp/5060), the audio rtp port (udp/7078) and the video rtp port (udp/9078). All those ports are configurable from linphone, but keeping 5060 for SIP is highly recommended.
    • Customising audio and video ports is recommended when using several linphone behind a same NAT so that they don't share same port numbers on the NAT. They must be even numbers.
  • Q: the video quality is awful ! I don't even recognize the person I'm talking with !
    • A: this is probably because the video stream is overflowing your internet connection bandwidth, resulting in truncated, dropped or late video packets which makes the image really awful. It is important that you tell linphone about the bandwidth limits (upload and download) of your internet connection. For that go to the 'codec' tab of the property box. Note that a minimum of 128 kbit/s are necessary in upload and download for video to work. The H264 plugin increases the video quality a lot.

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