diff --git a/icu4c/source/common/ucnv_cb.c b/icu4c/source/common/ucnv_cb.c
index f685085a183..b7a8ad3286c 100644
--- a/icu4c/source/common/ucnv_cb.c
+++ b/icu4c/source/common/ucnv_cb.c
@@ -21,6 +21,7 @@
 #include "unicode/utypes.h"
 #include "unicode/ucnv_cb.h"
 #include "ucnv_bld.h"
+#include "ucnv_cnv.h"
 #include "cmemory.h"
 
 /* need to update the offsets when the target moves. */
@@ -201,44 +202,19 @@ void ucnv_cbFromUWriteUChars(UConverterFromUnicodeArgs *args,
 
 void ucnv_cbFromUWriteSub (UConverterFromUnicodeArgs *args,
                            int32_t offsetIndex,
-                       UErrorCode * err)
+                           UErrorCode * err)
 {
-    char togo[5];
-    int32_t togoLen;
-
-    if(U_FAILURE(*err))
-    {
-      return;
+    if(U_FAILURE(*err)) {
+        return;
     }
 
-    /*In case we're dealing with a modal converter a la UCNV_EBCDIC_STATEFUL,
-    we need to make sure that the emitting of the substitution charater in the right mode*/
-    uprv_memcpy(togo, args->converter->subChar, togoLen = args->converter->subCharLen);
-    if (ucnv_getType(args->converter) == UCNV_EBCDIC_STATEFUL)
-    {
-        if ((args->converter->fromUnicodeStatus)&&(togoLen != 2))
-        {
-            togo[0] = UCNV_SI;
-            togo[1] = args->converter->subChar[0];
-            togo[2] = UCNV_SO;
-            togoLen = 3;
-        }
-        else if (!(args->converter->fromUnicodeStatus)&&(togoLen != 1))
-        {
-            togo[0] = UCNV_SO;
-            togo[1] = args->converter->subChar[0];
-            togo[2] = args->converter->subChar[1];
-            togo[3] = UCNV_SI;
-            togoLen = 4;
-        }
+    if(args->converter->sharedData->impl->writeSub!=NULL) {
+        args->converter->sharedData->impl->writeSub(args, offsetIndex, err);
+    } else {
+        ucnv_cbFromUWriteBytes(args,
+                               (const char *)args->converter->subChar, args->converter->subCharLen,
+                               offsetIndex, err);
     }
-
-    /*if we have enough space on the output buffer we just copy
-    the subchar there and update the pointer */  
-    ucnv_cbFromUWriteBytes(args, togo, togoLen, offsetIndex, err);
-
-
-    return;
 }
 
 void ucnv_cbToUWriteUChars (UConverterToUnicodeArgs *args,
diff --git a/icu4c/source/common/ucnv_cnv.h b/icu4c/source/common/ucnv_cnv.h
index 73f982ce04a..f2317f732f2 100644
--- a/icu4c/source/common/ucnv_cnv.h
+++ b/icu4c/source/common/ucnv_cnv.h
@@ -160,12 +160,22 @@ typedef UChar32 (*T_GetNextUCharFunction) (UConverterToUnicodeArgs *, UErrorCode
 typedef void (*UConverterGetStarters)(const UConverter* converter,
                                       UBool starters[256],
                                       UErrorCode *pErrorCode);
+
 /* If this function pointer is null or if the function returns null
  * the name field in static data struct should be returned by 
  * ucnv_getName() API function
  */
 typedef const char * (*UConverterGetName) (const UConverter *cnv);
 
+/**
+ * Write the codepage substitution character.
+ * If this function is not set, then ucnv_cbFromUWriteSub() writes
+ * the substitution character from UConverter.
+ * For stateful converters, it is typically necessary to handle this
+ * specificially for the converter in order to properly maintain the state.
+ */
+typedef void (*UConverterWriteSub) (UConverterFromUnicodeArgs *pArgs, int32_t offsetIndex, UErrorCode *pErrorCode);
+
 UBool CONVERSION_U_SUCCESS (UErrorCode err);
 
 void flushInternalUnicodeBuffer (UConverter * _this,
@@ -216,6 +226,7 @@ struct UConverterImpl {
 
     UConverterGetStarters getStarters;
     UConverterGetName getName;
+    UConverterWriteSub writeSub;
 };
 
 extern const UConverterSharedData