enable phone module on Galaxy Tab A I have a Galaxy Tab A running an intercom app. Problem is that this app uses telephone's default ringtone. To change it, i would need to change telephone's ringtone. Now, this tablet doesn't have the telehpone module enabled. Is there a way I can enable it so that i can access all OS telephone options (like ringtones)?
As long as your Tab A is not a carrier variant (e.g. AT&amp;T), you can just root the device and replace its default ringtone.

T280 is relatively scarce on development, but nevertheless here are threads (1, 2) dedicated to it and its LTE cousin (T285) on XDA-Developers. This post inside holds TWRP recovery for T280 for rooting and/or replacing. Since I don't have the device on hand, it's up to you to read through the thread, especially the ones after that post, to see how to flash and the precautions (it looks like the steps are more complicated than just flashing it in Odin).

For your purpose you don't actually need root - if you know what the corresponding ringtone file is, just use TWRP's built-in file manager to do the replacement. However, if you don't, it's advised to root so as to make things easier (previewing ringtone files on the fly).

The ringtone file should be somewhere under /system/media/audio. Although modifying audio files shouldn't pose risk, it's still strongly suggested that you make a full backup in TWRP before proceeding.