diff --git a/src/pdch_ul_controller.c b/src/pdch_ul_controller.c
index e6e22a2..1ead3e9 100644
--- a/src/pdch_ul_controller.c
+++ b/src/pdch_ul_controller.c
@@ -128,6 +128,29 @@
 	return 0;
 }
 
+/* Get next free (unreserved) FN which is not located in time before "start_fn" */
+uint32_t pdch_ulc_get_next_free_fn(struct pdch_ulc *ulc, uint32_t start_fn)
+{
+	struct rb_node *node;
+	struct pdch_ulc_node *it;
+	int res;
+	uint32_t check_fn = start_fn;
+
+	for (node = rb_first(&ulc->tree_root); node; node = rb_next(node)) {
+		it = container_of(node, struct pdch_ulc_node, node);
+		res = fn_cmp(it->fn, check_fn);
+		if (res > 0) { /* it->fn AFTER check_fn */
+			/* Next reserved FN is passed check_fn, hence it means check_fn is free */
+			return check_fn;
+		}
+		/* if it->fn < check_fn, simply continue iterating, we want to reach at least check_fn */
+		if (res == 0)/* it->fn == fn */
+			check_fn = fn_next_block(check_fn);
+		/* if it->fn < check_fn, simply continue iterating, we want to reach at least check_fn */
+	}
+	return check_fn;
+}
+
 static struct pdch_ulc_node *_alloc_node(struct pdch_ulc *ulc, uint32_t fn)
 {
 	struct pdch_ulc_node *node;
diff --git a/src/pdch_ul_controller.h b/src/pdch_ul_controller.h
index 731cbe1..5339e90 100644
--- a/src/pdch_ul_controller.h
+++ b/src/pdch_ul_controller.h
@@ -71,6 +71,7 @@
 bool pdch_ulc_fn_is_free(struct pdch_ulc *ulc, uint32_t fn);
 
 int pdch_ulc_get_next_free_rrbp_fn(struct pdch_ulc *ulc, uint32_t fn, uint32_t *poll_fn, unsigned int *rrbp);
+uint32_t pdch_ulc_get_next_free_fn(struct pdch_ulc *ulc, uint32_t start_fn);
 
 struct pdch_ulc_node *pdch_ulc_get_node(struct pdch_ulc *ulc, uint32_t fn);
 struct pdch_ulc_node *pdch_ulc_pop_node(struct pdch_ulc *ulc, uint32_t fn);
diff --git a/src/sba.c b/src/sba.c
index 3126893..ce44fa5 100644
--- a/src/sba.c
+++ b/src/sba.c
@@ -57,15 +57,18 @@
 struct gprs_rlcmac_sba *sba_alloc(void *ctx, struct gprs_rlcmac_pdch *pdch, uint8_t ta)
 {
 	struct gprs_rlcmac_sba *sba;
+	uint32_t start_fn;
+
 	sba = talloc_zero(ctx, struct gprs_rlcmac_sba);
 	if (!sba)
 		return NULL;
 
+	/* TODO: Increase start_fn dynamically based on AGCH queue load in the BTS: */
+	start_fn = next_fn(pdch->last_rts_fn, AGCH_START_OFFSET);
+
 	sba->pdch = pdch;
 	sba->ta = ta;
-
-	/* TODO: request ULC for next available FN instead of hardcoded AGCH_START_OFFSET */
-	sba->fn = next_fn(pdch->last_rts_fn, AGCH_START_OFFSET);
+	sba->fn = pdch_ulc_get_next_free_fn(pdch->ulc, start_fn);
 
 	pdch_ulc_reserve_sba(pdch->ulc, sba);
 	return sba;
diff --git a/tests/ulc/PdchUlcTest.cpp b/tests/ulc/PdchUlcTest.cpp
index 0099101..f0e8dd9 100644
--- a/tests/ulc/PdchUlcTest.cpp
+++ b/tests/ulc/PdchUlcTest.cpp
@@ -212,6 +212,30 @@
 	printf("=== end: %s ===\n", __FUNCTION__);
 }
 
+static void test_next_free_fn_sba()
+{
+	printf("=== start: %s ===\n", __FUNCTION__);
+	struct gprs_rlcmac_bts *bts = bts_alloc(the_pcu, 0);
+	struct gprs_rlcmac_pdch *pdch = &bts->trx[0].pdch[0];
+	struct gprs_rlcmac_sba *sba1, *sba2, *sba3, *sba4;
+
+	pdch->last_rts_fn = 52;
+	printf("*** ALLOC 1 SBA FN=%" PRIu32 ":\n", pdch->last_rts_fn);
+	sba1 = sba_alloc(bts, pdch, 0);
+	print_ulc_nodes(pdch->ulc);
+
+	pdch->last_rts_fn = 65;
+	printf("*** ALLOC 3 SBA FN=%" PRIu32 ":\n", pdch->last_rts_fn);
+	sba2 = sba_alloc(bts, pdch, 0);
+	sba3 = sba_alloc(bts, pdch, 0);
+	sba4 = sba_alloc(bts, pdch, 0);
+	print_ulc_nodes(pdch->ulc);
+	(void)sba1; (void)sba2; (void)sba3; (void)sba4;
+
+	talloc_free(bts);
+	printf("=== end: %s ===\n", __FUNCTION__);
+}
+
 int main(int argc, char **argv)
 {
 	tall_pcu_ctx = talloc_named_const(NULL, 1, "pdch_ulc test context");
@@ -231,6 +255,7 @@
 
 	test_reserve_multiple();
 	test_fn_wrap_around();
+	test_next_free_fn_sba();
 
 	talloc_free(the_pcu);
 	return EXIT_SUCCESS;
diff --git a/tests/ulc/PdchUlcTest.ok b/tests/ulc/PdchUlcTest.ok
index f20fb30..5bab5cc 100644
--- a/tests/ulc/PdchUlcTest.ok
+++ b/tests/ulc/PdchUlcTest.ok
@@ -247,3 +247,12 @@
 FN=39 type=POLL
 *** EXPIRE FN=43:
 === end: test_fn_wrap_around ===
+=== start: test_next_free_fn_sba ===
+*** ALLOC 1 SBA FN=52:
+FN=104 type=SBA
+*** ALLOC 3 SBA FN=65:
+FN=104 type=SBA
+FN=117 type=SBA
+FN=121 type=SBA
+FN=125 type=SBA
+=== end: test_next_free_fn_sba ===