Incoming calls are not working

Android

iOS

Windows Phone

Windows

Mac

Linux

Introduction:

Issues related to incoming calls are a common problem with voice over IP.

This article aims to outline the most common problems for the different operating systems as well as possible solutions and best practices for the most reliable incoming calls.

Most computers and phones do not use a fixed IP or are behind a NAT network.

VOIP servers use REGISTRATIONS to keep track of the current location of a user, this also serves as way to keep NAT bindings open on your home or office router.

iOS, Android and Windows Phone:

Make sure that Zoiper is allowed to run in the in the background

Android:

Open Zoiper -> go to settings -> Connectivity

Enable Keep Alive WiFi (unless you want to switch to 3g/4g when the wireless turns off).

Stay awake is on

Run in background is on

Then go to Android Settings -> Apps -> Zoiper -> Data Usage

Enable background data

Enable Unrestricted data usage

On Android 6.0 and above, please make sure Zoiper is on the whitelist for battery optimization. Zoiper should popup to allow it to add itself to the whitelist, but this will not work on some devices (Huawei, Xaomi,..) that come with their own battery optimization settings. Please manually add Zoiper to the battery optimization whitelist on such devices.

For Huawei devices, please see here.

iOS:

First make sure that Zoiper is allowed to use the cellular network.

To do so, go to the iOS settings -> Cellular

Scroll down to the "Use Cellular Data For" and make sure the option is enabled for Zoiper.

Currently the only way to be able to receive calls with Zoiper for iOS, when Zoiper is put on background is through enabling the PUSH proxy notifications.

You may do so from Zoiper -> Settings -> Incoming calls.

Keep in mind that due to iOS limitations, it is possible for incoming calls not to work when your internet connectivity stops (out of reach for WiFi and cellular at the same time) for some time. (This would depend on the length of the registration expiration timer your VoIP service provider has allowed.)

If event(registration expiration or call(INVITE)) comes to our PUSH proxy server and the phone is not reachable at that moment, the registration with it will be discarded. To renew it, you would need to manually re-launch Zoiper.

The default registration expiry values is: 2 600 000 seconds.

Some service providers allow very short registration expiration timers which do not work reliably with iOS(less than 1 hour).
Our PUSH proxy with not work at all with expiry timers below 10 minutes.

Please find and share with your VoIP service provider the requirements for reliable PUSH notifications here.

If your service provider is using shorter than 1 hour (3600 seconds) expiry timers, you may not receive calls when Zoiper is put on background even with PUSH enabled.

Windows Phone:

As Microsoft does not allow applications to run in background, Zoiper will not be able to run in background, only under the lock screen.
This means if you started any application after opening zoiper, then the incoming calls will no longer work.
The only thing to be done is to implement Push on your/VoIP provider's server.

http://www.zoiper.com/en/support/answer/for/windows-phone/105/Push_notifications

The NAT of the network is causing issues

You can verify if this is the case if Zoiper receives incoming calls immediately after a registration to the server, but after a few minutes incoming calls stop working. Or the issue appears only on specific networks.

The most likely culprit here is the short NAT port mapping on your home or office router.

When using UDP, most routers will drop the port mapping after a few minutes. This means zoiper would have to re-register every minute to keep the mapping alive.

When using TCP most routers will keep the connection for many hours (unless they run out of memory and start recycling port mappings).

Try switching the SIP account transport to TCP or TLS instead of UDP (if your provider or PBX supports it).

If your VoIP provider or PBX does not support TCP, try lowering the re-registration time in zoiper to 30s. or 1 minute. (This cannot be changed on iOS due to operating system limitations and on Android can be set only when the PUSH notifications are NOT enabled).

Keep in mind that an excessive reason of re-registrations might lead to temporary blocking by your VoIP provider.

Windows:

go to settings -> accounts -> your account -> advanced -> Network related.