diff --git a/src/encoding.cpp b/src/encoding.cpp
index 9dba4f6..2102a1e 100644
--- a/src/encoding.cpp
+++ b/src/encoding.cpp
@@ -899,13 +899,13 @@
  * \param num_chunks count the chunks (llc pdu data) within rlc/mac
  * \param data_block buffer holds rlc/mac data
  * \param is_final if this is the last rlc/mac within a TBF
+ * \param count_payload if not NULL save the written size of payload in bytes into it
  * \return the state of the rlc/mac like if there is more space for another chunk
  */
 static Encoding::AppendResult rlc_data_to_dl_append_gprs(
 	struct gprs_rlc_data_block_info *rdbi,
 	gprs_llc *llc, int *offset, int *num_chunks,
-	uint8_t *data_block,
-	bool is_final)
+	uint8_t *data_block, bool is_final, int *count_payload)
 {
 	int chunk;
 	int space;
@@ -930,6 +930,8 @@
 			*e_pointer |= 0x01;
 		/* fill only space */
 		llc->consume(data, space);
+		if (count_payload)
+			*count_payload = space;
 		/* return data block as message */
 		*offset = rdbi->data_len;
 		(*num_chunks)++;
@@ -947,6 +949,8 @@
 			*e_pointer |= 0x01;
 		/* fill space */
 		llc->consume(data, space);
+		if (count_payload)
+			*count_payload = space;
 		*offset = rdbi->data_len;
 		(*num_chunks)++;
 		rdbi->cv = 0;
@@ -974,6 +978,8 @@
 		// no need to set e_pointer nor increase delimiter
 		/* fill only space, which is 1 octet less than chunk */
 		llc->consume(data, space);
+		if (count_payload)
+			*count_payload = space;
 		/* return data block as message */
 		*offset = rdbi->data_len;
 		(*num_chunks)++;
@@ -999,6 +1005,8 @@
 	(*num_chunks)++;
 	/* copy (rest of) LLC frame to space and reset later */
 	llc->consume(data, chunk);
+	if (count_payload)
+		*count_payload = chunk;
 	data += chunk;
 	space -= chunk;
 	(*offset) += chunk;
@@ -1030,13 +1038,14 @@
  * \param num_chunks count the chunks (llc pdu data) within rlc/mac
  * \param data_block buffer holds rlc/mac data
  * \param is_final if this is the last rlc/mac within a TBF
+ * \param count_payload if not NULL save the written size of payload in bytes into it
  * \return the state of the rlc/mac like if there is more space for another chunk
  */
 static Encoding::AppendResult rlc_data_to_dl_append_egprs(
 	struct gprs_rlc_data_block_info *rdbi,
 	gprs_llc *llc, int *offset, int *num_chunks,
 	uint8_t *data_block,
-	bool is_final)
+	bool is_final, int *count_payload)
 {
 	int chunk;
 	int space;
@@ -1060,6 +1069,8 @@
 			chunk, space);
 		/* fill only space */
 		llc->consume(data, space);
+		if (count_payload)
+			*count_payload = space;
 		/* return data block as message */
 		*offset = rdbi->data_len;
 		(*num_chunks)++;
@@ -1074,6 +1085,8 @@
 			"header, and we are done\n", chunk, space);
 		/* fill space */
 		llc->consume(data, space);
+		if (count_payload)
+			*count_payload = space;
 		*offset = rdbi->data_len;
 		(*num_chunks)++;
 		rdbi->cv = 0;
@@ -1088,6 +1101,8 @@
 			chunk, space);
 		/* fill space */
 		llc->consume(data, space);
+		if (count_payload)
+			*count_payload = space;
 		*offset = rdbi->data_len;
 		(*num_chunks)++;
 		return Encoding::AR_NEED_MORE_BLOCKS;
@@ -1118,6 +1133,8 @@
 	(*num_chunks)++;
 	/* copy (rest of) LLC frame to space and reset later */
 	llc->consume(data, chunk);
+	if (count_payload)
+		*count_payload = chunk;
 	data += chunk;
 	space -= chunk;
 	(*offset) += chunk;
@@ -1183,21 +1200,23 @@
  * \param num_chunks count the chunks (llc pdu data) within rlc/mac
  * \param data_block buffer holds rlc/mac data
  * \param is_final if this is the last rlc/mac within a TBF
+ * \param count_payload if not NULL save the written size of payload in bytes into it
  * \return the state of the rlc/mac like if there is more space for another chunk
  */
 Encoding::AppendResult Encoding::rlc_data_to_dl_append(
 	struct gprs_rlc_data_block_info *rdbi, GprsCodingScheme cs,
 	gprs_llc *llc, int *offset, int *num_chunks,
-	uint8_t *data_block,
-	bool is_final)
+	uint8_t *data_block, bool is_final, int *count_payload)
 {
 	if (cs.isGprs())
 		return rlc_data_to_dl_append_gprs(rdbi,
-			llc, offset, num_chunks, data_block, is_final);
+			llc, offset, num_chunks, data_block, is_final,
+			count_payload);
 
 	if (cs.isEgprs())
 		return rlc_data_to_dl_append_egprs(rdbi,
-			llc, offset, num_chunks, data_block, is_final);
+			llc, offset, num_chunks, data_block, is_final,
+			count_payload);
 
 	LOGP(DRLCMACDL, LOGL_ERROR, "%s data block encoding not implemented\n",
 		cs.name());
diff --git a/src/encoding.h b/src/encoding.h
index 94e9a02..710de78 100644
--- a/src/encoding.h
+++ b/src/encoding.h
@@ -91,6 +91,5 @@
 	static AppendResult rlc_data_to_dl_append(
 		struct gprs_rlc_data_block_info *rdbi, GprsCodingScheme cs,
 		gprs_llc *llc, int *offset, int *num_chunks,
-		uint8_t *data,
-		bool is_final);
+		uint8_t *data, bool is_final, int *count_payload);
 };
diff --git a/src/tbf_dl.cpp b/src/tbf_dl.cpp
index da6628a..00adbc9 100644
--- a/src/tbf_dl.cpp
+++ b/src/tbf_dl.cpp
@@ -538,7 +538,7 @@
 		is_final = llc_queue()->size() == 0 && !keep_open(fn);
 
 		ar = Encoding::rlc_data_to_dl_append(rdbi, cs,
-			&m_llc, &write_offset, &num_chunks, data, is_final);
+			&m_llc, &write_offset, &num_chunks, data, is_final, NULL);
 
 		if (ar == Encoding::AR_NEED_MORE_BLOCKS)
 			break;
diff --git a/tests/edge/EdgeTest.cpp b/tests/edge/EdgeTest.cpp
index 96ea0c1..3e1c708 100644
--- a/tests/edge/EdgeTest.cpp
+++ b/tests/edge/EdgeTest.cpp
@@ -524,7 +524,7 @@
 	llc.put_frame(llc_data, 11);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_COMPLETED_SPACE_LEFT);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -535,7 +535,7 @@
 	llc.put_frame(llc_data, 26);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_COMPLETED_SPACE_LEFT);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -546,7 +546,7 @@
 	llc.put_frame(llc_data, 99);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_NEED_MORE_BLOCKS);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -571,7 +571,7 @@
 	llc.put_frame(llc_data, 20);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_NEED_MORE_BLOCKS);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -590,7 +590,7 @@
 	OSMO_ASSERT(llc.chunk_size() == 1);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_COMPLETED_SPACE_LEFT);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -601,7 +601,7 @@
 	llc.put_frame(llc_data, 99);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_NEED_MORE_BLOCKS);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -624,7 +624,7 @@
 	llc.put_frame(llc_data, 7);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_COMPLETED_SPACE_LEFT);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -635,7 +635,7 @@
 	llc.put_frame(llc_data, 11);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_COMPLETED_BLOCK_FILLED);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -659,7 +659,7 @@
 	llc.put_frame(llc_data, 99);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_NEED_MORE_BLOCKS);
 	OSMO_ASSERT(rdbi.e == 1);
@@ -682,7 +682,7 @@
 	llc.put_frame(llc_data, 20);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, true);
+		&llc, &write_offset, &num_chunks, data, true, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_COMPLETED_BLOCK_FILLED);
 	OSMO_ASSERT(rdbi.e == 1);
@@ -705,7 +705,7 @@
 	llc.put_frame(llc_data, 30);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_NEED_MORE_BLOCKS);
 	OSMO_ASSERT(rdbi.e == 1);
@@ -723,7 +723,7 @@
 	OSMO_ASSERT(llc.chunk_size() == 10);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_COMPLETED_SPACE_LEFT);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -734,7 +734,7 @@
 	llc.put_frame(llc_data, 99);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_NEED_MORE_BLOCKS);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -757,7 +757,7 @@
 	llc.put_frame(llc_data, 11);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_COMPLETED_SPACE_LEFT);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -768,7 +768,7 @@
 	llc.put_frame(llc_data, 26);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_COMPLETED_SPACE_LEFT);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -779,7 +779,7 @@
 	llc.put_frame(llc_data, 99);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_NEED_MORE_BLOCKS);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -809,7 +809,7 @@
 	llc.put_frame(llc_data, 15);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_COMPLETED_SPACE_LEFT);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -820,7 +820,7 @@
 	llc.put_frame(llc_data, 12);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_NEED_MORE_BLOCKS);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -840,7 +840,7 @@
 	OSMO_ASSERT(llc.chunk_size() == 0);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_COMPLETED_SPACE_LEFT);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -851,7 +851,7 @@
 	llc.put_frame(llc_data, 7);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_COMPLETED_SPACE_LEFT);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -863,7 +863,7 @@
 	llc.put_frame(llc_data, 18);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_COMPLETED_BLOCK_FILLED);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -886,7 +886,7 @@
 	llc.put_frame(llc_data, 6);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, false);
+		&llc, &write_offset, &num_chunks, data, false, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_COMPLETED_SPACE_LEFT);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -897,7 +897,7 @@
 	llc.put_frame(llc_data, 12);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, true);
+		&llc, &write_offset, &num_chunks, data, true, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_COMPLETED_BLOCK_FILLED);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -926,7 +926,7 @@
 	llc.put_frame(llc_data, rdbi.data_len);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, true);
+		&llc, &write_offset, &num_chunks, data, true, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_COMPLETED_BLOCK_FILLED);
 	OSMO_ASSERT(rdbi.e == 1);
@@ -950,7 +950,7 @@
 	llc.put_frame(llc_data, rdbi.data_len - 1);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, true);
+		&llc, &write_offset, &num_chunks, data, true, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_COMPLETED_BLOCK_FILLED);
 	OSMO_ASSERT(rdbi.e == 0);
@@ -975,7 +975,7 @@
 	llc.put_frame(llc_data, rdbi.data_len - 2);
 
 	ar = Encoding::rlc_data_to_dl_append(&rdbi, cs,
-		&llc, &write_offset, &num_chunks, data, true);
+		&llc, &write_offset, &num_chunks, data, true, NULL);
 
 	OSMO_ASSERT(ar == Encoding::AR_COMPLETED_BLOCK_FILLED);
 	OSMO_ASSERT(rdbi.e == 0);
