diff --git a/openbsc/src/gprs/sgsn_libgtp.c b/openbsc/src/gprs/sgsn_libgtp.c
new file mode 100644
index 0000000..fcaee8b
--- /dev/null
+++ b/openbsc/src/gprs/sgsn_libgtp.c
@@ -0,0 +1,421 @@
+/* GPRS SGSN integration with libgtp of OpenGGSN */
+
+/* (C) 2010 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2010 by On Waves
+ * 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 <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <getopt.h>
+#include <errno.h>
+#include <signal.h>
+#include <sys/fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include <osmocore/talloc.h>
+#include <osmocore/select.h>
+#include <osmocore/rate_ctr.h>
+
+#include <openbsc/signal.h>
+#include <openbsc/debug.h>
+#include <openbsc/sgsn.h>
+//#include <openbsc/gprs_ns.h>
+//#include <openbsc/gprs_bssgp.h>
+#include <openbsc/gprs_sgsn.h>
+#include <openbsc/gsm_04_08_gprs.h>
+
+#include <gtp.h>
+#include <pdp.h>
+
+struct ggsn_ctx {
+	unsigned int gtp_version;
+	struct in_addr remote_addr;
+	struct gsn_t *gsn;
+};
+
+const struct value_string gtp_cause_strs[] = {
+	{ GTPCAUSE_REQ_IMSI, "Request IMSI" },
+	{ GTPCAUSE_REQ_IMEI, "Request IMEI" },
+	{ GTPCAUSE_REQ_IMSI_IMEI, "Request IMSI and IMEI" },
+	{ GTPCAUSE_NO_ID_NEEDED, "No identity needed" },
+	{ GTPCAUSE_MS_REFUSES_X, "MS refuses" },
+	{ GTPCAUSE_MS_NOT_RESP_X, "MS is not GPRS responding" },
+	{ GTPCAUSE_ACC_REQ, "Request accepted" },
+	{ GTPCAUSE_NON_EXIST, "Non-existent" },
+	{ GTPCAUSE_INVALID_MESSAGE, "Invalid message format" },
+	{ GTPCAUSE_IMSI_NOT_KNOWN, "IMSI not known" },
+	{ GTPCAUSE_MS_DETACHED, "MS is GPRS detached" },
+	{ GTPCAUSE_MS_NOT_RESP, "MS is not GPRS responding" },
+	{ GTPCAUSE_MS_REFUSES, "MS refuses" },
+	{ GTPCAUSE_NO_RESOURCES, "No resources available" },
+	{ GTPCAUSE_NOT_SUPPORTED, "Service not supported" },
+	{ GTPCAUSE_MAN_IE_INCORRECT, "Mandatory IE incorrect" },
+	{ GTPCAUSE_MAN_IE_MISSING, "Mandatory IE missing" },
+	{ GTPCAUSE_OPT_IE_INCORRECT, "Optional IE incorrect" },
+	{ GTPCAUSE_SYS_FAIL, "System failure" },
+	{ GTPCAUSE_ROAMING_REST, "Roaming restrictions" },
+	{ GTPCAUSE_PTIMSI_MISMATCH, "P-TMSI Signature mismatch" },
+	{ GTPCAUSE_CONN_SUSP, "GPRS connection suspended" },
+	{ GTPCAUSE_AUTH_FAIL, "Authentication failure" },
+	{ GTPCAUSE_USER_AUTH_FAIL, "User authentication failed" },
+	{ GTPCAUSE_CONTEXT_NOT_FOUND, "Context not found" },
+	{ GTPCAUSE_ADDR_OCCUPIED, "All dynamic PDP addresses occupied" },
+	{ GTPCAUSE_NO_MEMORY, "No memory is available" },
+	{ GTPCAUSE_RELOC_FAIL, "Relocation failure" },
+	{ GTPCAUSE_UNKNOWN_MAN_EXTHEADER, "Unknown mandatory ext. header" },
+	{ GTPCAUSE_SEM_ERR_TFT, "Semantic error in TFT operation" },
+	{ GTPCAUSE_SYN_ERR_TFT, "Syntactic error in TFT operation" },
+	{ GTPCAUSE_SEM_ERR_FILTER, "Semantic errors in packet filter" },
+	{ GTPCAUSE_SYN_ERR_FILTER, "Syntactic errors in packet filter" },
+	{ GTPCAUSE_MISSING_APN, "Missing or unknown APN" },
+	{ GTPCAUSE_UNKNOWN_PDP, "Unknown PDP address or PDP type" },
+	{ 0, NULL }
+};
+
+/* generate a PDP context based on the IE's from the 04.08 message,
+ * and send the GTP create pdp context request to the GGSN */
+int sgsn_create_pdp_ctx(struct ggsn_ctx *ggsn, struct sgsn_mm_ctx *mmctx,
+			uint16_t nsapi, struct tlv_parsed *tp)
+{
+	struct sgsn_instance *sgsn = mmctx->sgsn;
+	struct pdp_t *pdp;
+	uint64_t imsi_ui64;
+	int rc;
+
+	rc = pdp_newpdp(&pdp, imsi_ui64, nsapi, NULL);
+	if (rc) {
+		LOGP(DGPRS, LOGL_ERROR, "Out of PDP Contexts\n");
+		return -ENOMEM;
+	}
+	//pdp->peer =	/* sockaddr_in of GGSN (receive) */
+	//pdp->ipif =	/* not used by library */
+	pdp->version = ggsn->gtp_version;
+	pdp->hisaddr0 =	ggsn->remote_addr;
+	pdp->hisaddr1 = ggsn->remote_addr;
+	//pdp->cch_pdp = 512;	/* Charging Flat Rate */
+
+	/* MS provided APN, subscription not verified */
+	pdp->selmode = 0x01;
+
+	/* IMSI, TEID/TEIC, FLLU/FLLC, TID, NSAPI set in pdp_newpdp */
+
+	/* FIXME: MSISDN in BCD format from mmctx */
+	//pdp->msisdn.l/.v
+
+	/* End User Address from GMM requested PDP address */
+	pdp->eua.l = TLVP_LEN(tp, OSMO_IE_GSM_REQ_PDP_ADDR);
+	if (pdp->eua.l > sizeof(pdp->eua.v))
+		pdp->eua.l = sizeof(pdp->eua.v);
+	memcpy(pdp->eua.v, TLVP_VAL(tp, OSMO_IE_GSM_REQ_PDP_ADDR),
+		pdp->eua.l);
+	/* Highest 4 bits of first byte need to be set to 1, otherwise
+	 * the IE is identical with the 04.08 PDP Address IE */
+	pdp->eua.v[0] |= 0xf0;
+
+	/* APN name from GMM */
+	pdp->apn_use.l = TLVP_LEN(tp, GSM48_IE_GSM_APN);
+	if (pdp->apn_use.l > sizeof(pdp->apn_use.v))
+		pdp->apn_use.l = sizeof(pdp->apn_use.v);
+	memcpy(pdp->apn_use.v, TLVP_VAL(tp, GSM48_IE_GSM_APN),
+		pdp->apn_use.l);
+
+	/* Protocol Configuration Options from GMM */
+	pdp->pco_req.l = TLVP_LEN(tp, GSM48_IE_GSM_PROTO_CONF_OPT);
+	if (pdp->pco_req.l > sizeof(pdp->pco_req.v))
+		pdp->pco_req.l = sizeof(pdp->pco_req.v);
+	memcpy(pdp->pco_req.v, TLVP_VAL(tp, GSM48_IE_GSM_PROTO_CONF_OPT),
+		pdp->pco_req.l);
+
+	/* QoS options from GMM */
+	pdp->qos_req.l = TLVP_LEN(tp, OSMO_IE_GSM_REQ_QOS);
+	if (pdp->qos_req.l > sizeof(pdp->qos_req.v))
+		pdp->qos_req.l = sizeof(pdp->qos_req.v);
+	memcpy(pdp->qos_req.v, TLVP_VAL(tp, OSMO_IE_GSM_REQ_QOS),
+		pdp->qos_req.l);
+
+	/* SGSN address for control plane */
+	pdp->gsnlc.l = sizeof(sgsn->cfg.gtp_listenaddr);
+	memcpy(pdp->gsnlc.v, &sgsn->cfg.gtp_listenaddr,
+		sizeof(sgsn->cfg.gtp_listenaddr));
+
+	/* SGSN address for user plane */
+	pdp->gsnlu.l = sizeof(sgsn->cfg.gtp_listenaddr);
+	memcpy(pdp->gsnlu.v, &sgsn->cfg.gtp_listenaddr,
+		sizeof(sgsn->cfg.gtp_listenaddr));
+
+	/* FIXME: change pdp state to 'requested' */
+
+	/* FIXME: pass along a pointer to the MM CTX */
+	return gtp_create_context_req(ggsn->gsn, pdp, mmctx);
+}
+
+/* The GGSN has confirmed the creation of a PDP Context */
+static int create_pdp_conf(struct pdp_t *pdp, void *cbp, int cause)
+{
+	struct sgsn_mm_ctx *mmctx = cbp;
+
+	DEBUGP(DGPRS, "Received CREATE PDP CTX CONF, cause=%d(%s)\n",
+		cause, get_value_string(gtp_cause_strs, cause));
+
+	/* Check for cause value if it was really successful */
+	if (cause < 0) {
+		LOGP(DGPRS, LOGL_NOTICE, "Create PDP ctx req timed out\n");
+		if (pdp->version == 1) {
+			pdp->version = 0;
+			gtp_create_context_req(mmctx->sgsn->gsn, pdp, cbp);
+			return 0;
+		} else {
+			pdp_freepdp(pdp);
+			return EOF;
+		}
+	}
+
+	/* Check for cause value if it was really successful */
+	if (cause != GTPCAUSE_ACC_REQ) {
+		pdp_freepdp(pdp);
+		return EOF;
+	}
+
+	/* FIXME: Determine MM ctx for the PDP ctx */
+	/* FIXME: Send PDP CTX ACT ACK/REJ to MS */
+	return 0;
+}
+
+/* If we receive a 04.08 DEACT PDP CTX REQ or GPRS DETACH, we need to
+ * look-up the PDP context and request its deletion from the SGSN */
+int sgsn_delete_pdp_ctx(struct ggsn_ctx *ggsn, struct sgsn_mm_ctx *mmctx,
+			struct tlv_parsed *tp)
+{
+	//return gtp_delete_context_req(gsn, pdp, cbp, teardown);
+}
+
+/* Confirmation of a PDP Context Delete */
+static int delete_pdp_conf(struct pdp_t *pdp, int cause)
+{
+	DEBUGP(DGPRS, "Received DELETE PDP CTX CONF, cause=%d(%s)\n",
+		cause, get_value_string(gtp_cause_strs, cause));
+	return 0;
+}
+
+/* Confirmation of an GTP ECHO request */
+static int echo_conf(int recovery)
+{
+	if (recovery < 0) {
+		DEBUGP(DGPRS, "GTP Echo Request timed out\n");
+		/* FIXME: if version == 1, retry with version 0 */
+	} else {
+		DEBUGP(DGPRS, "GTP Rx Echo Response\n");
+	}
+	return 0;
+}
+
+/* libgtp callback for confirmations */
+static int cb_conf(int type, int cause, struct pdp_t *pdp, void *cbp)
+{
+	DEBUGP(DGPRS, "libgtp cb_conf(type=%d, cause=%d, pdp=%p, cbp=%p)\n",
+		type, cause, pdp, cbp);
+
+	if (cause == EOF)
+		LOGP(DGPRS, LOGL_ERROR, "libgtp EOF (type=%u, pdp=%p, cbp=%p)\n",
+			type, pdp, cbp);
+
+	switch (type) {
+	case GTP_ECHO_REQ:
+		return echo_conf(cause);
+	case GTP_CREATE_PDP_REQ:
+		return create_pdp_conf(pdp, cbp, cause);
+	case GTP_DELETE_PDP_REQ:
+		return delete_pdp_conf(pdp, cause);
+	default:
+		break;
+	}
+	return 0;
+}
+
+/* Called whenever a PDP context is deleted for any reason */
+static int cb_delete_context(struct pdp_t *pdp)
+{
+	LOGP(DGPRS, LOGL_INFO, "PDP Context was deleted\n");
+	return 0;
+}
+
+/* Called when we receive a Version Not Supported message */
+static int cb_unsup_ind(struct sockaddr_in *peer)
+{
+	LOGP(DGPRS, LOGL_INFO, "GTP Version not supported Indication "
+		"from %s:%u\n", inet_ntoa(peer->sin_addr),
+		ntohs(peer->sin_port));
+	return 0;
+}
+
+/* Called when we receive a Supported Ext Headers Notification */
+static int cb_extheader_ind(struct sockaddr_in *peer)
+{
+	LOGP(DGPRS, LOGL_INFO, "GTP Supported Ext Headers Noficiation "
+		"from %s:%u\n", inet_ntoa(peer->sin_addr),
+		ntohs(peer->sin_port));
+	return 0;
+}
+
+/* Called whenever we recive a DATA packet */
+static int cb_data_ind(struct pdp_t *pdp, void *packet, unsigned int len)
+{
+	DEBUGP(DGPRS, "GTP DATA IND from GGSN, length=%u\n", len);
+
+	return 0;
+}
+
+/* libgtp select loop integration */
+static int sgsn_gtp_fd_cb(struct bsc_fd *fd, unsigned int what)
+{
+	struct sgsn_instance *sgi = fd->data;
+	int rc;
+
+	if (!(what & BSC_FD_READ))
+		return 0;
+
+	switch (fd->priv_nr) {
+	case 0:
+		rc = gtp_decaps0(sgi->gsn);
+		break;
+	case 1:
+		rc = gtp_decaps1c(sgi->gsn);
+		break;
+	case 2:
+		rc = gtp_decaps1u(sgi->gsn);
+		break;
+	}
+	return rc;
+}
+
+static void timeval_normalize(struct timeval *tv)
+{
+	unsigned int sec = tv->tv_usec / 1000000;
+	tv->tv_sec += sec;
+	tv->tv_usec -= sec * 1000000;
+}
+
+/* diff = a - b */
+static int timeval_diff(struct timeval *diff,
+			struct timeval *a,
+			struct timeval *b)
+{
+	/* Step 1: normalize input values */
+	timeval_normalize(a);
+	timeval_normalize(b);
+
+	if (b->tv_sec > a->tv_sec ||
+	    b->tv_sec == a->tv_sec && b->tv_usec > a->tv_usec) {
+		b->tv_sec = b->tv_usec = 0;
+		return -ERANGE;
+	}
+
+	if (b->tv_usec > a->tv_usec) {
+		a->tv_sec -= 1;
+		a->tv_usec += 1000000;
+	}
+
+	diff->tv_usec = a->tv_usec - b->tv_usec;
+	diff->tv_sec = a->tv_sec - b->tv_sec;
+
+	return 0;
+}
+
+static void sgsn_gtp_tmr_start(struct sgsn_instance *sgi)
+{
+	struct timeval now, next, diff;
+
+	/* Retrieve next retransmission as struct timeval */
+	gtp_retranstimeout(sgi->gsn, &next);
+
+	/* Calculate the difference to now */
+	gettimeofday(&now, NULL);
+	timeval_diff(&diff, &next, &now);
+
+	/* re-schedule the timer */
+	bsc_schedule_timer(&sgi->gtp_timer, diff.tv_sec, diff.tv_usec/1000);
+}
+
+/* timer callback for libgtp retransmissions and ping */
+static void sgsn_gtp_tmr_cb(void *data)
+{
+	struct sgsn_instance *sgi = data;
+
+	/* Do all the retransmissions as needed */
+	gtp_retrans(sgi->gsn);
+
+	sgsn_gtp_tmr_start(sgi);
+}
+
+int sgsn_gtp_init(struct sgsn_instance *sgi)
+{
+	int rc;
+	struct gsn_t *gsn;
+
+	rc = gtp_new(&sgi->gsn, sgi->cfg.gtp_statedir,
+		     &sgi->cfg.gtp_listenaddr.sin_addr, GTP_MODE_SGSN);
+	if (rc) {
+		LOGP(DGPRS, LOGL_ERROR, "Failed to create GTP: %d\n", rc);
+		return rc;
+	}
+	gsn = sgi->gsn;
+
+	sgi->gtp_fd0.fd = gsn->fd0;
+	sgi->gtp_fd0.priv_nr = 0;
+	sgi->gtp_fd0.data = sgi;
+	sgi->gtp_fd0.cb = sgsn_gtp_fd_cb;
+	rc = bsc_register_fd(&sgi->gtp_fd0);
+	if (rc < 0)
+		return rc;
+
+	sgi->gtp_fd1c.fd = gsn->fd1c;
+	sgi->gtp_fd1c.priv_nr = 1;
+	sgi->gtp_fd1c.data = sgi;
+	sgi->gtp_fd1c.cb = sgsn_gtp_fd_cb;
+	bsc_register_fd(&sgi->gtp_fd1c);
+	if (rc < 0)
+		return rc;
+
+	sgi->gtp_fd1u.fd = gsn->fd1u;
+	sgi->gtp_fd1u.priv_nr = 2;
+	sgi->gtp_fd1u.data = sgi;
+	sgi->gtp_fd1u.cb = sgsn_gtp_fd_cb;
+	bsc_register_fd(&sgi->gtp_fd1u);
+	if (rc < 0)
+		return rc;
+
+	/* Start GTP re-transmission timer */
+	sgi->gtp_timer.cb = sgsn_gtp_tmr_cb;
+	sgsn_gtp_tmr_start(sgi);
+
+	/* Register callbackcs with libgtp */
+	gtp_set_cb_delete_context(gsn, cb_delete_context);
+	gtp_set_cb_conf(gsn, cb_conf);
+	gtp_set_cb_data_ind(gsn, cb_data_ind);
+	gtp_set_cb_unsup_ind(gsn, cb_unsup_ind);
+	gtp_set_cb_extheader_ind(gsn, cb_extheader_ind);
+
+	return 0;
+}