diff --git a/openbsc/src/transaction.c b/openbsc/src/transaction.c
new file mode 100644
index 0000000..e917cdd
--- /dev/null
+++ b/openbsc/src/transaction.c
@@ -0,0 +1,134 @@
+/* GSM 04.07 Transaction handling */
+
+/* (C) 2009 by Harald Welte <laforge@gnumonks.org>
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <openbsc/transaction.h>
+#include <openbsc/gsm_data.h>
+#include <openbsc/mncc.h>
+#include <openbsc/debug.h>
+#include <openbsc/talloc.h>
+#include <openbsc/gsm_subscriber.h>
+#include <openbsc/gsm_04_08.h>
+#include <openbsc/mncc.h>
+#include <openbsc/paging.h>
+
+static void *tall_trans_ctx;
+
+struct gsm_trans *trans_find_by_id(struct gsm_lchan *lchan, u_int8_t trans_id)
+{
+	struct gsm_trans *trans;
+	struct gsm_network *net = lchan->ts->trx->bts->network;
+
+	llist_for_each_entry(trans, &net->trans_list, entry) {
+		if (trans->lchan == lchan && trans->transaction_id == trans_id)
+			return trans;
+	}
+	return NULL;
+}
+
+struct gsm_trans *trans_find_by_callref(struct gsm_network *net,
+					u_int32_t callref)
+{
+	struct gsm_trans *trans;
+
+	llist_for_each_entry(trans, &net->trans_list, entry) {
+		if (trans->callref == callref)
+			return trans;
+	}
+	return NULL;
+}
+
+struct gsm_trans *trans_alloc(struct gsm_subscriber *subscr,
+			      u_int8_t protocol, u_int8_t trans_id,
+			      u_int32_t callref)
+{
+	struct gsm_trans *trans;
+
+	DEBUGP(DCC, "subscr=%p, subscr->net=%p\n", subscr, subscr->net);
+
+	trans = talloc_zero(tall_trans_ctx, struct gsm_trans);
+	if (!trans)
+		return NULL;
+
+	trans->subscr = subscr;
+	subscr_get(trans->subscr);
+
+	trans->protocol = protocol;
+	trans->transaction_id = trans_id;
+	trans->callref = callref;
+
+	llist_add_tail(&trans->entry, &subscr->net->trans_list);
+
+	return trans;
+}
+
+void trans_free(struct gsm_trans *trans)
+{
+	struct gsm_bts *bts;
+
+	switch (trans->protocol) {
+	case GSM48_PDISC_CC:
+		_gsm48_cc_trans_free(trans);
+		break;
+	}
+
+	if (trans->lchan)
+		put_lchan(trans->lchan);
+
+	if (!trans->lchan && trans->subscr && trans->subscr->net) {
+		/* Stop paging on all bts' */
+		bts = NULL;
+		do {
+			bts = gsm_bts_by_lac(trans->subscr->net,
+					     trans->subscr->lac, bts);
+			if (!bts)
+				break;
+			/* Stop paging */
+			paging_request_stop(bts, trans->subscr, NULL);
+		} while (1);
+	}
+
+	if (trans->subscr)
+		subscr_put(trans->subscr);
+
+	llist_del(&trans->entry);
+
+	talloc_free(trans);
+}
+
+#if 0
+int trans_assign_trans_id(struct gsm_subscriber *subscr,
+			  u_int8_t protocol, u_int8_t ti_flag)
+{
+	struct gsm_network *net = subscr->net;
+	struct gsm_trans *trans;
+	unsigned int used_tid_bitmask = 0;
+
+	/* generate bitmask of already-used TIDs for this (subscr,proto) */
+	llist_for_each_entry(trans, &net->trans_list, entry) {
+		if (trans->subscr != subscr ||
+		    trans->protocol != protocol ||
+		    trans->transaction_id == 0xff)
+			continue;
+		used_tid_bitmask |= (1 << trans->transaction_id);
+	}
+
+}
+#endif