you're support screens definition looks fine, have you any permission there are not available for tablets, like sms permission?
An Workaround for you:
in you're Manifest declare the extra permission as following:
<uses-feature android:name="android.hardware.telephony" android:required="false" > </uses-feature>
in you're Java Code you can/must handle this section in there you want to send the sms, you can do this with the following:
PackageManager pm = getPackageManager();
boolean hasTelephony = pm.hasSystemFeature(PackageManager.FEATURE_TELEPHONY);
with this you can do the rest