The call recording feature is only available on Android devices. Recording SIM / Whatsapp calls is prohibited by Apple's security guidelines, so you cannot record SIM / Whatsapp calls on iOS.

If you are based in India, Indonesia or Russia, your device might come with a built-in call recorder, in which case you might be able to use that one as the recording source for Salestrail. To set it up, please follow the steps in this article: https://help.salestrail.io/en/articles/10002181-setting-up-call-recording-on-a-device-that-has-a-built-in-call-recorder
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If you are from the US, Europe, South America, Africa, Australia or an Asian country where devices usually don't come with a built-in call recorder, please follow the steps in this article: https://help.salestrail.io/en/articles/9258756-how-to-record-your-calls-using-the-salestrail-recorder-apk