diff --git a/lib_com/options.h b/lib_com/options.h
index 2512ff1d0cfb05b0488be3f7e68b19779a2f547f..18dc45e90c29ff8b211d94777102f047f11bbc76 100644
--- a/lib_com/options.h
+++ b/lib_com/options.h
@@ -98,6 +98,7 @@
 #define FIX_2385_GETTCXONLY                             /* FhG: issue 2385 : harmonizing getTcxonly_ivas_fx() and getTcxonly_ivas_fx() functions */
 #define FIX_2196_UNREACHABLE_CODE_IN_OSBA_STEREO_OUTPUT /* FhG: remove unreachable code in ivas_osba_stereo_add_channels */
 #define FIX_OUTPUT_FRAME                                /* VA: harmonize "output_frame" parameter usage to correspond to FLP */
+#define HARMONIZE_ISSUE_2435_WRITETNSDATA               /* FhG basop 2435: Harmonize WriteTnsData*_fx(), EncodeTnsData*_fx() */
 
 /* #################### End BE switches ################################## */
 
diff --git a/lib_com/prot_fx.h b/lib_com/prot_fx.h
index 896c3fe72427794d15785ce2e6e698cfd6c5d2cf..8d22557a8417aea3416683345e3d17d923711b68 100644
--- a/lib_com/prot_fx.h
+++ b/lib_com/prot_fx.h
@@ -8188,6 +8188,7 @@ void GetParameters_fx(
     Word16 *pnBits             // Q0
 );
 
+#ifndef HARMONIZE_ISSUE_2435_WRITETNSDATA
 void EncodeTnsData_ivas_fx(
     STnsConfig const *pTnsConfig, /* i  : TNS Configuration struct          */
     STnsData const *pTnsData,     /* i  : TNS data struct (quantized param) */
@@ -8195,6 +8196,15 @@ void EncodeTnsData_ivas_fx(
     Word16 *pnSize,               /* o  : number of written parameters      Q0*/
     Word16 *pnBits                /* o  : number of written bits            Q0*/
 );
+#else
+void EncodeTnsData_ivas_fx(
+    STnsConfig const *pTnsConfig, /* i  : TNS Configuration struct          */
+    STnsData const *pTnsData,     /* i  : TNS data struct (quantized param) */
+    Word16 *stream,               /* o  : internal data stream           Q0 */
+    Word16 *pnSize,               /* o  : number of written parameters   Q0 */
+    Word16 *pnBits                /* o  : number of written bits         Q0 */
+);
+#endif
 
 void SetParameters(
     ParamsBitMap const *paramsBitMap,
@@ -10808,6 +10818,7 @@ void ResetTnsData_flt(
 void ClearTnsFilterCoefficients_flt(
     STnsFilter *pTnsFilter );
 
+#ifndef HARMONIZE_ISSUE_2435_WRITETNSDATA
 void EncodeTnsData(
     STnsConfig const *pTnsConfig, /* i  : TNS Configuration struct          */
     STnsData const *pTnsData,     /* i  : TNS data struct (quantized param) */
@@ -10815,6 +10826,7 @@ void EncodeTnsData(
     Word16 *pnSize,               /* o  : number of written parameters      */
     Word16 *pnBits                /* o  : number of written bits            */
 );
+#endif
 
 void WriteTnsData(
     const STnsConfig *pTnsConfig, /* i  : TNS Configuration struct          */
@@ -10823,6 +10835,7 @@ void WriteTnsData(
     BSTR_ENC_HANDLE hBstr,        /* o  : bitstream                         */
     Word16 *pnBits                /* o  : number of written bits            */
 );
+
 #ifndef HARMONIZE_READ_DECODE_TNS
 void ReadTnsData_ivas(
     STnsConfig const *pTnsConfig,
diff --git a/lib_enc/cod_tcx_fx.c b/lib_enc/cod_tcx_fx.c
index e73ef35a2246bb1da92f1703eba430b256d4f68e..db451247697fde2b4fcacff5ceff171b98199d0a 100644
--- a/lib_enc/cod_tcx_fx.c
+++ b/lib_enc/cod_tcx_fx.c
@@ -5506,7 +5506,11 @@ void TNSAnalysisStereo_fx(
 
                 st->hTcxEnc->tnsData[k].tnsOnWhitenedSpectra = st->hTcxEnc->bTnsOnWhithenedSpectra[k];
                 move16();
+#ifdef HARMONIZE_ISSUE_2435_WRITETNSDATA
+                EncodeTnsData_fx( st->hTcxCfg->pCurrentTnsConfig, &st->hTcxEnc->tnsData[k], param_core[ch] + k * NPRM_DIV + 1 + NOISE_FILL_RANGES + LTPSIZE, tnsSize[ch] + k, tnsBits[ch] + k );
+#else
                 EncodeTnsData_ivas_fx( st->hTcxCfg->pCurrentTnsConfig, &st->hTcxEnc->tnsData[k], param_core[ch] + k * NPRM_DIV + 1 + NOISE_FILL_RANGES + LTPSIZE, tnsSize[ch] + k, tnsBits[ch] + k );
+#endif
             }
 
             IF( EQ_16( st->hTcxEnc->transform_type[k], TCX_5 ) )
diff --git a/lib_enc/enc_prm_fx.c b/lib_enc/enc_prm_fx.c
index 3a4a043e3f194a9bf89dd08d86786d4354bcf8fc..f72a955a8e8b055e0ac0c7ea7c0b3e7c06d72bd7 100644
--- a/lib_enc/enc_prm_fx.c
+++ b/lib_enc/enc_prm_fx.c
@@ -749,7 +749,13 @@ void enc_prm_fx(
 
         IF( st->hTcxCfg->fIsTNSAllowed )
         {
+#ifndef HARMONIZE_ISSUE_2435_WRITETNSDATA
+
             WriteTnsData_fx( st->hTcxCfg->pCurrentTnsConfig, prm + j, &nTnsParams, st, &nTnsBits );
+#else
+            WriteTnsData_fx( st->hTcxCfg->pCurrentTnsConfig, prm + j, &nTnsParams, st->hBstr, &nTnsBits );
+#endif // !HARMONIZE_ISSUE_2435_WRITETNSDATA
+
             j = add( j, nTnsParams ); /* Q0 */
         }
 
@@ -899,8 +905,13 @@ void enc_prm_fx(
             {
 
                 SetTnsConfig( st->hTcxCfg, 0, ( last_core == ACELP_CORE ) && ( k == 0 ) );
-
+#ifndef HARMONIZE_ISSUE_2435_WRITETNSDATA
                 WriteTnsData_fx( st->hTcxCfg->pCurrentTnsConfig, prm + j, &nTnsParams, st, &nTnsBits );
+#else
+                WriteTnsData_fx( st->hTcxCfg->pCurrentTnsConfig, prm + j, &nTnsParams, st->hBstr, &nTnsBits );
+#endif // !HARMONIZE_ISSUE_2435_WRITETNSDATA
+
+
                 j = add( j, nTnsParams );
             }
 
@@ -1208,7 +1219,11 @@ void writeTCXparam_fx(
                 }
                 ELSE
                 {
+#ifndef HARMONIZE_ISSUE_2435_WRITETNSDATA
                     WriteTnsData_ivas_fx( st->hTcxCfg->pCurrentTnsConfig, prm + j, &nTnsParams, hBstr, &nTnsBits );
+#else
+                    WriteTnsData_fx( st->hTcxCfg->pCurrentTnsConfig, prm + j, &nTnsParams, hBstr, &nTnsBits );
+#endif // !HARMONIZE_ISSUE_2435_WRITETNSDATA
                 }
                 IF( no_param_tns )
                 {
diff --git a/lib_enc/prot_fx_enc.h b/lib_enc/prot_fx_enc.h
index ebe4f4aa523bdf4d2f15fa693a93fb036a81a01a..43dda3a78fb4633fad488e23ed3a43f7c62666b9 100644
--- a/lib_enc/prot_fx_enc.h
+++ b/lib_enc/prot_fx_enc.h
@@ -1486,28 +1486,45 @@ Word16 DetectTnsFilt_ivas_fx(
     Word16 *predictionGain        /* o  : TNS prediction gain        Q=7    */
 );
 
-
+#ifdef HARMONIZE_ISSUE_2435_WRITETNSDATA
+void EncodeTnsData_fx(
+    STnsConfig const *pTnsConfig,
+    STnsData const *pTnsData,
+    Word16 *stream,
+    Word16 *pnSize,
+    Word16 *pnBits );
+#else
 Word16 EncodeTnsData_fx(
     STnsConfig const *pTnsConfig,
     STnsData const *pTnsData,
     Word16 *stream,
     Word16 *pnSize,
     Word16 *pnBits );
+#endif
 
+#ifdef HARMONIZE_ISSUE_2435_WRITETNSDATA
 Word16 WriteTnsData_fx(
     STnsConfig const *pTnsConfig,
     Word16 const *stream,
     Word16 *pnSize,
-    Encoder_State *st,
+    BSTR_ENC_HANDLE hBstr,
     Word16 *pnBits );
+#endif // HARMONIZE_ISSUE_2435_WRITETNSDATA
 
+#ifndef HARMONIZE_ISSUE_2435_WRITETNSDATA
+Word16 WriteTnsData_fx(
+    STnsConfig const *pTnsConfig,
+    Word16 const *stream,
+    Word16 *pnSize,
+    Encoder_State *st,
+    Word16 *pnBits );
 Word16 WriteTnsData_ivas_fx(
     STnsConfig const *pTnsConfig,
     Word16 const *stream,
     Word16 *pnSize,
     BSTR_ENC_HANDLE hBstr,
     Word16 *pnBits );
-
+#endif // !HARMONIZE_ISSUE_2435_WRITETNSDATA
 void subband_FFT_fx(
     Word32 **Sr,      /*(i) real part of the CLDFB*/
     Word32 **Si,      /*(i) imag part of the CLDFB*/
diff --git a/lib_enc/tns_base_enc_fx.c b/lib_enc/tns_base_enc_fx.c
index be7c067608e36ab3bfd92cfde03a2925d5580857..1b9f67de7c15eb41aa9fd6648d443e5a8e2157fd 100644
--- a/lib_enc/tns_base_enc_fx.c
+++ b/lib_enc/tns_base_enc_fx.c
@@ -697,6 +697,7 @@ Word16 DetectTnsFilt_ivas_fx(
     return ( pTnsData->nFilters > 0 );
 }
 
+#ifndef HARMONIZE_ISSUE_2435_WRITETNSDATA
 Word16 EncodeTnsData_fx( STnsConfig const *pTnsConfig, STnsData const *pTnsData, Word16 *stream, Word16 *pnSize, Word16 *pnBits )
 {
 
@@ -724,7 +725,17 @@ Word16 EncodeTnsData_fx( STnsConfig const *pTnsConfig, STnsData const *pTnsData,
 
     return TNS_NO_ERROR;
 }
+#endif
 
+#ifdef HARMONIZE_ISSUE_2435_WRITETNSDATA
+void EncodeTnsData_fx(
+    STnsConfig const *pTnsConfig, /* i  : TNS Configuration struct          */
+    STnsData const *pTnsData,     /* i  : TNS data struct (quantized param) */
+    Word16 *stream,               /* o  : internal data stream              Q0*/
+    Word16 *pnSize,               /* o  : number of written parameters      Q0*/
+    Word16 *pnBits                /* o  : number of written bits            Q0*/
+)
+#else
 void EncodeTnsData_ivas_fx(
     STnsConfig const *pTnsConfig, /* i  : TNS Configuration struct          */
     STnsData const *pTnsData,     /* i  : TNS data struct (quantized param) */
@@ -732,6 +743,7 @@ void EncodeTnsData_ivas_fx(
     Word16 *pnSize,               /* o  : number of written parameters      Q0*/
     Word16 *pnBits                /* o  : number of written bits            Q0*/
 )
+#endif
 {
     *pnSize = 0;
     move16();
@@ -770,7 +782,7 @@ void EncodeTnsData_ivas_fx(
 
     return;
 }
-
+#ifndef HARMONIZE_ISSUE_2435_WRITETNSDATA
 Word16 WriteTnsData_fx( STnsConfig const *pTnsConfig, Word16 const *stream, Word16 *pnSize, Encoder_State *st, Word16 *pnBits )
 {
 
@@ -794,7 +806,13 @@ Word16 WriteTnsData_fx( STnsConfig const *pTnsConfig, Word16 const *stream, Word
 
     return TNS_NO_ERROR;
 }
+#endif // !HARMONIZE_ISSUE_2435_WRITETNSDATA
+
+#ifndef HARMONIZE_ISSUE_2435_WRITETNSDATA
 Word16 WriteTnsData_ivas_fx( STnsConfig const *pTnsConfig, Word16 const *stream, Word16 *pnSize, BSTR_ENC_HANDLE hBstr, Word16 *pnBits )
+#else
+Word16 WriteTnsData_fx( STnsConfig const *pTnsConfig, Word16 const *stream, Word16 *pnSize, BSTR_ENC_HANDLE hBstr, Word16 *pnBits )
+#endif // !HARMONIZE_ISSUE_2435_WRITETNSDATA
 {
     IF( GT_16( pTnsConfig->nMaxFilters, 1 ) )
     {