Push Notifications is currently our recommended method for receiving calls when Acrobits Softphone (or Groundwire) is not in the foreground. We have other articles for configuring Push Notifications and troubleshooting issues, this article is intended to familiarize our users with Push Notifications and how they differ from multitasking.
We'll start by stating that Push Notifications is not Multitasking. To the end user, they may not look much different in use, but they work very differently. It's also important to state that we support multitasking as well. Many users confuse Push Notifications with Multitasking and because of this think that Push Notifications are their only option for receiving calls when the softphone is not in the foreground. Most SIP clients on iOS only offer one option (i.e. Push Notifications OR multitasking, usually multitasking). Both Acrobits Softphone and Groundwire support Push Notification as well as multitasking. We realize different users have different needs and we want to give as many options as possible.
To learn more about multitasking on Acrobits Softphone and Groundwire, check out the articles below.
Now more about how Push Notifications actually work. Once you enable Push Notifications in Acrobits Softphone or Groundwire, we register your SIP account on SIPIS (our server that handles Push Notifications) whenever you exit the app (whether you move it to the background or close it). To your SIP provider or PBX, it looks just like any other registration, making you available for calls. Once SIPIS recieves an invite (incoming call), we send the relevant information to Apple, who sends you a Push Notification. Once you accept the Push Notification, Acrobits Softphone or Groundwire will open and SIPIS will connect the call to your device. At this point SIP Traffic will continue to be routed through SIPIS, while audio will go directly to the device.
Before we continue, I should note that this is just a simplified explanation of how Push Notifications work solely intended to give the average user a basic understanding of the process. If you have specific technical questions not answered here, feel free to open a ticket.
Now that you have a basic understanding of how Push Notifications work, we'll explain why this is our recommended method. There are two main reasons.
1. Battery Life - Since SIPIS does all the work, using Push Notifications has a negligible effect on battery life. Since your average user often charges their iPhone once a day (and some heavy users feel like they always have it plugged in), this is a pretty important benefit and the main reason we recommend using Push Notifications.
2. Resources - iOS has made it clear that Push is the way to go and the way iOS works is built around this. There was one other option for VoIP backgrounding, but iOS recently deprecated the feature. Now, if you use multitasking, the app is always in use, even when in the background, which could effect the overall performance of the phone. iOS support some types of multi tasking (like listening to music while doing something else or the multiple app screens on some recent iPads), but it is not really intended for an app to be running in the background all the time.
There also a couple reasons I should mention why users may not be able to or might not want to use Push Notifications.
1. SIP Server must be reachable from the public internet - Since SIPIS needs to be able to register your account, those with a PBX with a configuration that does not allow you to register from the public internet will not be able to use push Notifications. (If it's simply a firewall issue where you need to know the IPs that SIPIS will register from, just open a ticket and we can provide that information.)
2. Security - Acrobits Softphone must transfer your account details to SIPIS over a https secure connection in order for Push Notifications to work. But this should not be a concern for most users. SIPIS is very secure and we have never had a security issue. I think the only users who should be concerned with this would be those using the Softphone or Groundwire with a PBX and their company has very strict security policies. If that's the case, just show this article to your PBX administrator. It should have enough information for them to determine if they will allow you to use Push Notifications. And please note, this only applies when using Push Notifications. This does not occur if you use one of our methods for multitasking. (as mentioned earlier, many users confuse Push Notifications with multitasking)
Also, while Push Notifications will work with the vast majority of SIP providers, there will probably be a few providers with a configuration that just won't be compatible with Push Notifications. If you have any issues using Push Notifications that you aren't able to resolve after reading our other articles on Push Notifications, please open a ticket. We can usually determine quickly what the issue is and whether it can be resolved.
To configure push notifications, read the following article.
For a comparison of Push Notifications and multitasking, read this article.