Handover between networks

All our apps use the same SIP stack developed by Acrobits. Use this forum to ask any technical questions about our SIP protocol implementation.
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Handover between networks

Post by Brian » Mon Oct 17, 2016 2:20 pm

How do you handle the situation when the mobile device loses wifi signal in the middle of the call and the network changes to cellular data? Will the call be dropped?

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Re: Handover between networks

Post by admin » Tue Oct 18, 2016 4:19 pm

Our SIP stack has a sophisticated mechanism to handle network changes. The default behaviour is to minimise changes in the media channel to avoid dropouts during handovers.

For example, if you make a call using cellular data, walk into a wifi-covered area, your device switches to wifi, but the original cellular data connection is still working. We'll stick to the cellular network interface to provide seamless audio experience.

In your example, when the wifi is lost, the apps will detect that the current network is no longer available and issue a re-INVITE with the new addresses for media, which will probably be cellular data network. In case there is no other network available, the app will wait for up to 30 seconds for any network to come up.

For Cloud Softphone apps, this behaviour is configurable via provisioning: the key "networkChangeResetStrategy" can be set to issue re-invite "always", "if_different" and "if_needed" (which is the default).

Users of Acrobits SDK can further customise this behaviour by implementing a function which receives the list of available networks on every network change even and returns them sorted by preference.

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