I have and S3 and when the NE is working, have no problems. I double checked by dialing #48 and I am under network extender coverage. I use the NE to make calls and text. I also have 4G LTE which is used for mms and data. But, unfortunately the NE hasn't worked since 3/10/13. Fast flashing red light on System and Solid steady Magenta on GPS. Luckily, (knocking on wood) I can still make calls and not having any dropped calls. I like having the NE just in case.
Nemetoad, I agree that if 3 different phone manufacturers are having this issue that it appears to be an issue with the extender and not the devices. Are all of your lights blue on the extender? Dial #48 while in the house to see if you are connected to the extender. This will give you a message letting you know whether you're connected to the extender or not. If everything appears okay with the connection, and still dropping calls, we may need to submit a trouble ticket to our network team. We have a technical support team that handles network extenders extensively. Have you contacted our technical support at 800-922-0204 previously about this issue?