Q: My iPhone XS Max uses the RoboKiller app that's supposed to intercept junk phone calls. I expected it to block the 15 to 25 junk calls I was getting every day, but to let through callers who were in my phone's contact list. Unfortunately, RoboKiller blocks calls from my contacts list and lets the junk calls through. I also can't remove the app from my phone. What's wrong?
Dan Johnson, Brooklyn Park
A: Many users of the RoboKiller phone app have reported similar problems.
The app's developer has acknowledged there is a flaw in newer versions of RoboKiller. Another source of problems is that RoboKiller must be set up differently in order to work on some cellular phone networks. A third problem is that the app is difficult to remove.
The app's problems revolve around the way it's supposed to work. While calls arrive at your phone via the cellular network, some or all of them are then rerouted over the internet to a RoboKiller server for evaluation. (This is done using VoIP, or Voice over Internet Protocol technology. As a result, the amount of traffic on the internet can affect how fast this routing happens, and the quality of the resulting phone call.) The RoboKiller server determines if the calls forwarded to it are legitimate or unwanted. It sends the legitimate ones back to your phone via VoIP, and sends unwanted calls to RoboKiller's voice mail system.
The developers of RoboKiller said in July that a flaw in the app may be preventing some legitimate calls from reaching the customer's phone, including some calls from people listed in the phone's contacts.
In addition, the phone settings that connect RoboKiller can be troublesome. The preferred setting is called "Conditional Call Forwarding." When it's used, acceptable calls (including from numbers in the phone's "contacts list") immediately go to the phone. Only questionable calls are sent to the RoboKiller server for review.
But some cellular companies (it's unclear which ones) don't support Conditional Call Forwarding. Customers of those companies must use a phone setting called "Unconditional Call Forwarding," in which all incoming calls go directly to the RoboKiller server, which then sends the legitimate ones back to the phone. The app's developers said that calls handled by Unconditional Call Forwarding are those most vulnerable to the app's software flaw.
