You can access the Google Play Store from your Sony Ericsson ER-LT15I.
To do this, please follow the instructions below.
1. From the home (or main) display screen on your Sony Ericsson ER-LT15I, press (tap on) Apps.
2. On the Apps menu screen, select (tap on) the Google Play Store icon to access and download applications.
3. search Record Calls or click https://play.google.com/store/search?q=record%20calls&c=apps&hl=en
The method for setting up (i.e. installing) an application to record telephone conversations may vary, depending on the app being used and/or your Sony Ericsson ER-LT15I operating system.
Please be aware of any legal requirements or implications when using third party software to record calls.