See TS 23.040 9.2.3.9 returns true if this is a "replace short message"
SMS
Syntax
[get: Android.Runtime.Register("isReplace", "()Z", "GetIsReplaceHandler")]
public virtual
bool IsReplace { get; }
Value
Documentation for this section has not yet been entered.
Remarks
Requirements
Namespace: Android.Telephony
Assembly: Mono.Android (in Mono.Android.dll)
Assembly Versions: 0.0.0.0
Since: Added in API level 4