A call recording depends on Android version. Moreover, it's vendor (manufacturer) specific problem, because everyone can modify Android open source code. Because of that reason, the Call Utils can't record calls on any devices. In some specific cases the Call Utils can record only your voice and not the other party.
We'll be pleased if you'll write us detail information about your not working device. Please, test call recording on your device before you pay a subscription. You can revoke subscription, in the free trial period.
The Call Utils for Salesforce was tested and works perfectly on these devices (with original not-rooted Android OS):
Call Utils audio recording currenty doesn't work with:
If you have a bad experience, please contact us with detail information about your device. We'll do our best. Thank you!