diff --git a/src/sgsn/gprs_sm.c b/src/sgsn/gprs_sm.c
new file mode 100644
index 0000000..8cf5c5d
--- /dev/null
+++ b/src/sgsn/gprs_sm.c
@@ -0,0 +1,749 @@
+/* Section "9.5 GPRS Session Management Messages"
+ * 3GPP TS 04.08 version 7.21.0 Release 1998 / ETSI TS 100 940 V7.21.0 */
+
+/* (C) 2009-2015 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2010 by On-Waves
+ * (C) 2019 by sysmocom s.f.m.c. GmbH <info@sysmocom.de>
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+
+#include "bscconfig.h"
+
+#include <osmocom/core/rate_ctr.h>
+#include <osmocom/core/tdef.h>
+#include <osmocom/gsm/apn.h>
+#include <osmocom/gprs/gprs_bssgp.h>
+
+#include <osmocom/sgsn/gprs_sm.h>
+#include <osmocom/sgsn/gprs_gmm.h>
+#include <osmocom/sgsn/gprs_utils.h>
+#include <osmocom/sgsn/sgsn.h>
+#include <osmocom/sgsn/debug.h>
+#include <osmocom/sgsn/gprs_llc.h>
+#include <osmocom/sgsn/gprs_sndcp.h>
+#include <osmocom/sgsn/gprs_ranap.h>
+
+extern void *tall_sgsn_ctx;
+
+/* 3GPP TS 04.08 sec 6.1.3.4.3(.a) "Abnormal cases" */
+#define T339X_MAX_RETRANS 4
+
+static const struct tlv_definition gsm48_sm_att_tlvdef = {
+	.def = {
+		[GSM48_IE_GSM_APN]		= { TLV_TYPE_TLV, 0 },
+		[GSM48_IE_GSM_PROTO_CONF_OPT]	= { TLV_TYPE_TLV, 0 },
+		[GSM48_IE_GSM_PDP_ADDR]		= { TLV_TYPE_TLV, 0 },
+		[GSM48_IE_GSM_AA_TMR]		= { TLV_TYPE_TV, 1 },
+		[GSM48_IE_GSM_NAME_FULL]	= { TLV_TYPE_TLV, 0 },
+		[GSM48_IE_GSM_NAME_SHORT]	= { TLV_TYPE_TLV, 0 },
+		[GSM48_IE_GSM_TIMEZONE]		= { TLV_TYPE_FIXED, 1 },
+		[GSM48_IE_GSM_UTC_AND_TZ]	= { TLV_TYPE_FIXED, 7 },
+		[GSM48_IE_GSM_LSA_ID]		= { TLV_TYPE_TLV, 0 },
+	},
+};
+
+static struct gsm48_qos default_qos = {
+	.delay_class = 4,	/* best effort */
+	.reliab_class = GSM48_QOS_RC_LLC_UN_RLC_ACK_DATA_PROT,
+	.peak_tput = GSM48_QOS_PEAK_TPUT_32000bps,
+	.preced_class = GSM48_QOS_PC_NORMAL,
+	.mean_tput = GSM48_QOS_MEAN_TPUT_BEST_EFFORT,
+	.traf_class = GSM48_QOS_TC_INTERACTIVE,
+	.deliv_order = GSM48_QOS_DO_UNORDERED,
+	.deliv_err_sdu = GSM48_QOS_ERRSDU_YES,
+	.max_sdu_size = GSM48_QOS_MAXSDU_1520,
+	.max_bitrate_up = GSM48_QOS_MBRATE_63k,
+	.max_bitrate_down = GSM48_QOS_MBRATE_63k,
+	.resid_ber = GSM48_QOS_RBER_5e_2,
+	.sdu_err_ratio = GSM48_QOS_SERR_1e_2,
+	.handling_prio = 3,
+	.xfer_delay = 0x10,	/* 200ms */
+	.guar_bitrate_up = GSM48_QOS_MBRATE_0k,
+	.guar_bitrate_down = GSM48_QOS_MBRATE_0k,
+	.sig_ind = 0,	/* not optimised for signalling */
+	.max_bitrate_down_ext = 0,	/* use octet 9 */
+	.guar_bitrate_down_ext = 0,	/* use octet 13 */
+};
+
+/* GPRS SESSION MANAGEMENT */
+
+static void pdpctx_timer_cb(void *_mm);
+
+static void pdpctx_timer_rearm(struct sgsn_pdp_ctx *pdp, unsigned int T)
+{
+	unsigned long seconds;
+	if (osmo_timer_pending(&pdp->timer))
+		LOGPDPCTXP(LOGL_ERROR, pdp, "Scheduling PDP timer %u while old "
+			"timer %u pending\n", T, pdp->T);
+	seconds = osmo_tdef_get(sgsn->cfg.T_defs, T, OSMO_TDEF_S, -1);
+	osmo_timer_schedule(&pdp->timer, seconds, 0);
+}
+
+static void pdpctx_timer_start(struct sgsn_pdp_ctx *pdp, unsigned int T)
+{
+	if (osmo_timer_pending(&pdp->timer))
+		LOGPDPCTXP(LOGL_ERROR, pdp, "Starting PDP timer %u while old "
+			"timer %u pending\n", T, pdp->T);
+	pdp->T = T;
+	pdp->num_T_exp = 0;
+
+	osmo_timer_setup(&pdp->timer, pdpctx_timer_cb, pdp);
+	pdpctx_timer_rearm(pdp, pdp->T);
+}
+
+static void pdpctx_timer_stop(struct sgsn_pdp_ctx *pdp, unsigned int T)
+{
+	if (pdp->T != T)
+		LOGPDPCTXP(LOGL_ERROR, pdp, "Stopping PDP timer %u but "
+			"%u is running\n", T, pdp->T);
+	osmo_timer_del(&pdp->timer);
+}
+
+void pdp_ctx_detach_mm_ctx(struct sgsn_pdp_ctx *pdp)
+{
+	/* Detach from MM context */
+	llist_del(&pdp->list);
+	pdp->mm = NULL;
+
+	/* stop timer 3395 */
+	pdpctx_timer_stop(pdp, 3395);
+}
+
+#if 0
+static void msgb_put_pdp_addr_ipv4(struct msgb *msg, uint32_t ipaddr)
+{
+	uint8_t v[6];
+
+	v[0] = PDP_TYPE_ORG_IETF;
+	v[1] = PDP_TYPE_N_IETF_IPv4;
+	*(uint32_t *)(v+2) = htonl(ipaddr);
+
+	msgb_tlv_put(msg, GSM48_IE_GSM_PDP_ADDR, sizeof(v), v);
+}
+
+static void msgb_put_pdp_addr_ppp(struct msgb *msg)
+{
+	uint8_t v[2];
+
+	v[0] = PDP_TYPE_ORG_ETSI;
+	v[1] = PDP_TYPE_N_ETSI_PPP;
+
+	msgb_tlv_put(msg, GSM48_IE_GSM_PDP_ADDR, sizeof(v), v);
+}
+#endif
+
+/* Chapter 9.4.18 */
+static int _tx_status(struct msgb *msg, uint8_t cause,
+		      struct sgsn_mm_ctx *mmctx)
+{
+	struct gsm48_hdr *gh;
+
+	/* MMCTX might be NULL! */
+
+	DEBUGP(DMM, "<- GPRS MM STATUS (cause: %s)\n",
+		get_value_string(gsm48_gmm_cause_names, cause));
+
+	gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh) + 1);
+	gh->proto_discr = GSM48_PDISC_SM_GPRS;
+	gh->msg_type = GSM48_MT_GSM_STATUS;
+	gh->data[0] = cause;
+
+	return gsm48_gmm_sendmsg(msg, 0, mmctx, true);
+}
+
+static int gsm48_tx_sm_status(struct sgsn_mm_ctx *mmctx, uint8_t cause)
+{
+	struct msgb *msg = gsm48_msgb_alloc_name("GSM 04.08 SM STATUS");
+
+	mmctx2msgid(msg, mmctx);
+	return _tx_status(msg, cause, mmctx);
+}
+
+/* 3GPP TS 24.008 § 9.5.2: Activate PDP Context Accept */
+int gsm48_tx_gsm_act_pdp_acc(struct sgsn_pdp_ctx *pdp)
+{
+	struct msgb *msg = gsm48_msgb_alloc_name("GSM 04.08 PDP ACC");
+	struct gsm48_hdr *gh;
+	uint8_t transaction_id = pdp->ti ^ 0x8; /* flip */
+
+	LOGPDPCTXP(LOGL_INFO, pdp, "<- ACTIVATE PDP CONTEXT ACK\n");
+	rate_ctr_inc(&sgsn->rate_ctrs->ctr[CTR_PDP_ACTIVATE_ACCEPT]);
+
+	mmctx2msgid(msg, pdp->mm);
+
+	gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh));
+	gh->proto_discr = GSM48_PDISC_SM_GPRS | (transaction_id << 4);
+	gh->msg_type = GSM48_MT_GSM_ACT_PDP_ACK;
+
+	/* Negotiated LLC SAPI */
+	msgb_v_put(msg, pdp->sapi);
+
+	/* FIXME: copy QoS parameters from original request */
+	//msgb_lv_put(msg, pdp->lib->qos_neg.l, pdp->lib->qos_neg.v);
+	msgb_lv_put(msg, sizeof(default_qos), (uint8_t *)&default_qos);
+
+	/* Radio priority 10.5.7.2 */
+	msgb_v_put(msg, pdp->lib->radio_pri);
+
+	/* PDP address */
+	/* 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->lib->eua.v[0] &= ~0xf0;
+	msgb_tlv_put(msg, GSM48_IE_GSM_PDP_ADDR,
+		     pdp->lib->eua.l, pdp->lib->eua.v);
+	pdp->lib->eua.v[0] |= 0xf0;
+
+	/* Optional: Protocol configuration options (FIXME: why 'req') */
+	if (pdp->lib->pco_req.l)
+		msgb_tlv_put(msg, GSM48_IE_GSM_PROTO_CONF_OPT,
+			     pdp->lib->pco_req.l, pdp->lib->pco_req.v);
+
+	/* Optional: Packet Flow Identifier */
+
+	return gsm48_gmm_sendmsg(msg, 0, pdp->mm, true);
+}
+
+/* 3GPP TS 24.008 § 9.5.3: Activate PDP Context reject */
+int gsm48_tx_gsm_act_pdp_rej(struct sgsn_mm_ctx *mm, uint8_t tid,
+			     uint8_t cause, uint8_t pco_len, uint8_t *pco_v)
+{
+	struct msgb *msg = gsm48_msgb_alloc_name("GSM 04.08 PDP REJ");
+	struct gsm48_hdr *gh;
+	uint8_t transaction_id = tid ^ 0x8; /* flip */
+
+	LOGMMCTXP(LOGL_NOTICE, mm, "<- ACTIVATE PDP CONTEXT REJ: %s\n",
+		  get_value_string(gsm48_gsm_cause_names, cause));
+	rate_ctr_inc(&sgsn->rate_ctrs->ctr[CTR_PDP_ACTIVATE_REJECT]);
+
+	mmctx2msgid(msg, mm);
+
+	gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh));
+	gh->proto_discr = GSM48_PDISC_SM_GPRS | (transaction_id << 4);
+	gh->msg_type = GSM48_MT_GSM_ACT_PDP_REJ;
+
+	msgb_v_put(msg, cause);
+	if (pco_len && pco_v)
+		msgb_tlv_put(msg, GSM48_IE_GSM_PROTO_CONF_OPT, pco_len, pco_v);
+
+	return gsm48_gmm_sendmsg(msg, 0, mm, true);
+}
+
+/* 3GPP TS 24.008 § 9.5.8: Deactivate PDP Context Request */
+static int _gsm48_tx_gsm_deact_pdp_req(struct sgsn_mm_ctx *mm, uint8_t tid,
+					uint8_t sm_cause, bool teardown)
+{
+	struct msgb *msg = gsm48_msgb_alloc_name("GSM 04.08 PDP DET REQ");
+	struct gsm48_hdr *gh;
+	uint8_t transaction_id = tid ^ 0x8; /* flip */
+	uint8_t tear_down_ind = (0x9 << 4) | (!!teardown);
+
+	LOGMMCTXP(LOGL_INFO, mm, "<- DEACTIVATE PDP CONTEXT REQ\n");
+	rate_ctr_inc(&sgsn->rate_ctrs->ctr[CTR_PDP_DL_DEACTIVATE_REQUEST]);
+
+	mmctx2msgid(msg, mm);
+
+	gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh));
+	gh->proto_discr = GSM48_PDISC_SM_GPRS | (transaction_id << 4);
+	gh->msg_type = GSM48_MT_GSM_DEACT_PDP_REQ;
+
+	msgb_v_put(msg, sm_cause);
+	msgb_v_put(msg, tear_down_ind);
+
+	return gsm48_gmm_sendmsg(msg, 0, mm, true);
+}
+int gsm48_tx_gsm_deact_pdp_req(struct sgsn_pdp_ctx *pdp, uint8_t sm_cause, bool teardown)
+{
+	pdpctx_timer_start(pdp, 3395);
+
+	return _gsm48_tx_gsm_deact_pdp_req(pdp->mm, pdp->ti, sm_cause, teardown);
+}
+
+/* 3GPP TS 24.008 § 9.5.9: Deactivate PDP Context Accept */
+static int _gsm48_tx_gsm_deact_pdp_acc(struct sgsn_mm_ctx *mm, uint8_t tid)
+{
+	struct msgb *msg = gsm48_msgb_alloc_name("GSM 04.08 PDP DET ACC");
+	struct gsm48_hdr *gh;
+	uint8_t transaction_id = tid ^ 0x8; /* flip */
+
+	LOGMMCTXP(LOGL_INFO, mm, "<- DEACTIVATE PDP CONTEXT ACK\n");
+	rate_ctr_inc(&sgsn->rate_ctrs->ctr[CTR_PDP_DL_DEACTIVATE_ACCEPT]);
+
+	mmctx2msgid(msg, mm);
+
+	gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh));
+	gh->proto_discr = GSM48_PDISC_SM_GPRS | (transaction_id << 4);
+	gh->msg_type = GSM48_MT_GSM_DEACT_PDP_ACK;
+
+	return gsm48_gmm_sendmsg(msg, 0, mm, true);
+}
+int gsm48_tx_gsm_deact_pdp_acc(struct sgsn_pdp_ctx *pdp)
+{
+	return _gsm48_tx_gsm_deact_pdp_acc(pdp->mm, pdp->ti);
+}
+
+static int activate_ggsn(struct sgsn_mm_ctx *mmctx,
+		struct sgsn_ggsn_ctx *ggsn, const uint8_t transaction_id,
+		const uint8_t req_nsapi, const uint8_t req_llc_sapi,
+		struct tlv_parsed *tp, int destroy_ggsn)
+{
+	struct sgsn_pdp_ctx *pdp;
+
+	LOGMMCTXP(LOGL_DEBUG, mmctx, "Using GGSN %u\n", ggsn->id);
+	ggsn->gsn = sgsn->gsn;
+	pdp = sgsn_create_pdp_ctx(ggsn, mmctx, req_nsapi, tp);
+	if (!pdp)
+		return -1;
+
+	/* Store SAPI and Transaction Identifier */
+	pdp->sapi = req_llc_sapi;
+	pdp->ti = transaction_id;
+	pdp->destroy_ggsn = destroy_ggsn;
+
+	return 0;
+}
+
+static void ggsn_lookup_cb(void *arg, int status, int timeouts, struct hostent *hostent)
+{
+	struct sgsn_ggsn_ctx *ggsn;
+	struct sgsn_ggsn_lookup *lookup = arg;
+	struct in_addr *addr = NULL;
+	char buf[INET_ADDRSTRLEN];
+
+	/* The context is gone while we made a request */
+	if (!lookup->mmctx) {
+		talloc_free(lookup->orig_msg);
+		talloc_free(lookup);
+		return;
+	}
+
+	if (status != ARES_SUCCESS) {
+		struct sgsn_mm_ctx *mmctx = lookup->mmctx;
+
+		LOGMMCTXP(LOGL_ERROR, mmctx, "DNS query failed.\n");
+
+		/* Need to try with three digits now */
+		if (lookup->state == SGSN_GGSN_2DIGIT) {
+			char *hostname;
+			int rc;
+
+			lookup->state = SGSN_GGSN_3DIGIT;
+			hostname = osmo_apn_qualify_from_imsi(mmctx->imsi,
+					lookup->apn_str, 1);
+			LOGMMCTXP(LOGL_DEBUG, mmctx,
+				"Going to query %s\n", hostname);
+			rc = sgsn_ares_query(sgsn, hostname,
+					ggsn_lookup_cb, lookup);
+			if (rc != 0) {
+				LOGMMCTXP(LOGL_ERROR, mmctx, "Couldn't start GGSN\n");
+				goto reject_due_failure;
+			}
+			return;
+		}
+
+		LOGMMCTXP(LOGL_ERROR, mmctx, "Couldn't resolve GGSN\n");
+		goto reject_due_failure;
+	}
+
+	if (hostent->h_length != sizeof(struct in_addr)) {
+		LOGMMCTXP(LOGL_ERROR, lookup->mmctx,
+			"Wrong addr size(%zu)\n", sizeof(struct in_addr));
+		goto reject_due_failure;
+	}
+
+	/* Get the first addr from the list */
+	addr = (struct in_addr *) hostent->h_addr_list[0];
+	if (!addr) {
+		LOGMMCTXP(LOGL_ERROR, lookup->mmctx, "No host address.\n");
+		goto reject_due_failure;
+	}
+
+	ggsn = sgsn_ggsn_ctx_alloc(UINT32_MAX);
+	if (!ggsn) {
+		LOGMMCTXP(LOGL_ERROR, lookup->mmctx, "Failed to create ggsn.\n");
+		goto reject_due_failure;
+	}
+	ggsn->remote_addr = *addr;
+	LOGMMCTXP(LOGL_NOTICE, lookup->mmctx,
+		  "Selected %s as GGSN.\n",
+		  inet_ntop(AF_INET, addr, buf, sizeof(buf)));
+
+	/* forget about the ggsn look-up */
+	lookup->mmctx->ggsn_lookup = NULL;
+
+	activate_ggsn(lookup->mmctx, ggsn, lookup->ti, lookup->nsapi,
+			lookup->sapi, &lookup->tp, 1);
+
+	/* Now free it */
+	talloc_free(lookup->orig_msg);
+	talloc_free(lookup);
+	return;
+
+reject_due_failure:
+	gsm48_tx_gsm_act_pdp_rej(lookup->mmctx, lookup->ti,
+				GMM_CAUSE_NET_FAIL, 0, NULL);
+	lookup->mmctx->ggsn_lookup = NULL;
+	talloc_free(lookup->orig_msg);
+	talloc_free(lookup);
+}
+
+static int do_act_pdp_req(struct sgsn_mm_ctx *mmctx, struct msgb *msg, bool *delete)
+{
+	struct gsm48_hdr *gh = (struct gsm48_hdr *) msgb_gmmh(msg);
+	struct gsm48_act_pdp_ctx_req *act_req = (struct gsm48_act_pdp_ctx_req *) gh->data;
+	uint8_t req_qos_len, req_pdpa_len;
+	uint8_t *req_qos, *req_pdpa;
+	struct tlv_parsed tp;
+	uint8_t transaction_id = gsm48_hdr_trans_id(gh);
+	struct sgsn_ggsn_ctx *ggsn;
+	struct sgsn_pdp_ctx *pdp;
+	enum gsm48_gsm_cause gsm_cause;
+	char apn_str[GSM_APN_LENGTH] = { 0, };
+	char *hostname;
+	int rc;
+	struct gprs_llc_lle *lle;
+	char buf[INET_ADDRSTRLEN];
+
+	LOGMMCTXP(LOGL_INFO, mmctx, "-> ACTIVATE PDP CONTEXT REQ: SAPI=%u NSAPI=%u ",
+		act_req->req_llc_sapi, act_req->req_nsapi);
+
+	/* FIXME: length checks! */
+	req_qos_len = act_req->data[0];
+	req_qos = act_req->data + 1;	/* 10.5.6.5 */
+	req_pdpa_len = act_req->data[1 + req_qos_len];
+	req_pdpa = act_req->data + 1 + req_qos_len + 1;	/* 10.5.6.4 */
+
+	switch (req_pdpa[0] & 0xf) {
+	case 0x0:
+		DEBUGPC(DMM, "ETSI ");
+		break;
+	case 0x1:
+		DEBUGPC(DMM, "IETF ");
+		break;
+	case 0xf:
+		DEBUGPC(DMM, "Empty ");
+		break;
+	}
+
+	switch (req_pdpa[1]) {
+	case 0x21:
+		DEBUGPC(DMM, "IPv4 ");
+		if (req_pdpa_len >= 6) {
+			struct in_addr ia;
+			ia.s_addr = ntohl(*((uint32_t *) (req_pdpa+2)));
+			DEBUGPC(DMM, "%s ", inet_ntop(AF_INET, &ia, buf, sizeof(buf)));
+		}
+		break;
+	case 0x57:
+		DEBUGPC(DMM, "IPv6 ");
+		if (req_pdpa_len >= 18) {
+			/* FIXME: print IPv6 address */
+		}
+		break;
+	default:
+		DEBUGPC(DMM, "0x%02x ", req_pdpa[1]);
+		break;
+	}
+
+	LOGPC(DMM, LOGL_INFO, "\n");
+
+	/* Check if NSAPI is out of range (TS 04.65 / 7.2) */
+	if (act_req->req_nsapi < 5 || act_req->req_nsapi > 15) {
+		/* Send reject with GSM_CAUSE_INV_MAND_INFO */
+		return gsm48_tx_gsm_act_pdp_rej(mmctx, transaction_id,
+						GSM_CAUSE_INV_MAND_INFO,
+						0, NULL);
+	}
+
+	/* Optional: Access Point Name, Protocol Config Options */
+	if (req_pdpa + req_pdpa_len < msg->data + msg->len)
+		tlv_parse(&tp, &gsm48_sm_att_tlvdef, req_pdpa + req_pdpa_len,
+			  (msg->data + msg->len) - (req_pdpa + req_pdpa_len), 0, 0);
+	else
+		memset(&tp, 0, sizeof(tp));
+
+
+	/* put the non-TLV elements in the TLV parser structure to
+	 * pass them on to the SGSN / GTP code */
+	tp.lv[OSMO_IE_GSM_REQ_QOS].len = req_qos_len;
+	tp.lv[OSMO_IE_GSM_REQ_QOS].val = req_qos;
+	tp.lv[OSMO_IE_GSM_REQ_PDP_ADDR].len = req_pdpa_len;
+	tp.lv[OSMO_IE_GSM_REQ_PDP_ADDR].val = req_pdpa;
+
+	/* Check if NSAPI is already in use */
+	pdp = sgsn_pdp_ctx_by_nsapi(mmctx, act_req->req_nsapi);
+	if (pdp) {
+		/* We already have a PDP context for this TLLI + NSAPI tuple */
+		if (pdp->sapi == act_req->req_llc_sapi &&
+		    pdp->ti == transaction_id) {
+			/* This apparently is a re-transmission of a PDP CTX
+			 * ACT REQ (our ACT ACK must have got dropped) */
+			rc = gsm48_tx_gsm_act_pdp_acc(pdp);
+			if (rc < 0)
+				return rc;
+
+			if (pdp->mm->ran_type == MM_CTX_T_GERAN_Gb) {
+				/* Also re-transmit the SNDCP XID message */
+				lle = &pdp->mm->gb.llme->lle[pdp->sapi];
+				rc = sndcp_sn_xid_req(lle,pdp->nsapi);
+				if (rc < 0)
+					return rc;
+			}
+
+			return 0;
+		}
+
+		/* Send reject with GSM_CAUSE_NSAPI_IN_USE */
+		return gsm48_tx_gsm_act_pdp_rej(mmctx, transaction_id,
+						GSM_CAUSE_NSAPI_IN_USE,
+						0, NULL);
+	}
+
+	if (mmctx->ggsn_lookup) {
+		if (mmctx->ggsn_lookup->sapi == act_req->req_llc_sapi &&
+			mmctx->ggsn_lookup->ti == transaction_id) {
+			LOGMMCTXP(LOGL_NOTICE, mmctx,
+				"Re-transmission while doing look-up. Ignoring.\n");
+			return 0;
+		}
+	}
+
+	/* Only increment counter for a real activation, after we checked
+	 * for re-transmissions */
+	rate_ctr_inc(&mmctx->ctrg->ctr[GMM_CTR_PDP_CTX_ACT]);
+
+	/* Determine GGSN based on APN and subscription options */
+	ggsn = sgsn_mm_ctx_find_ggsn_ctx(mmctx, &tp, &gsm_cause, apn_str);
+	if (ggsn)
+		return activate_ggsn(mmctx, ggsn, transaction_id,
+				act_req->req_nsapi, act_req->req_llc_sapi,
+				&tp, 0);
+
+	if (strlen(apn_str) == 0)
+		goto no_context;
+	if (!sgsn->cfg.dynamic_lookup)
+		goto no_context;
+
+	/* schedule a dynamic look-up */
+	mmctx->ggsn_lookup = talloc_zero(tall_sgsn_ctx, struct sgsn_ggsn_lookup);
+	if (!mmctx->ggsn_lookup)
+		goto no_context;
+
+	mmctx->ggsn_lookup->state = SGSN_GGSN_2DIGIT;
+	mmctx->ggsn_lookup->mmctx = mmctx;
+	strcpy(mmctx->ggsn_lookup->apn_str, apn_str);
+
+	mmctx->ggsn_lookup->orig_msg = msg;
+	mmctx->ggsn_lookup->tp = tp;
+
+	mmctx->ggsn_lookup->ti = transaction_id;
+	mmctx->ggsn_lookup->nsapi = act_req->req_nsapi;
+	mmctx->ggsn_lookup->sapi = act_req->req_llc_sapi;
+
+	hostname = osmo_apn_qualify_from_imsi(mmctx->imsi,
+				mmctx->ggsn_lookup->apn_str, 0);
+
+	LOGMMCTXP(LOGL_DEBUG, mmctx, "Going to query %s\n", hostname);
+	rc = sgsn_ares_query(sgsn, hostname,
+				ggsn_lookup_cb, mmctx->ggsn_lookup);
+	if (rc != 0) {
+		LOGMMCTXP(LOGL_ERROR, mmctx, "Failed to start ares query.\n");
+		goto no_context;
+	}
+	*delete = 0;
+
+	return 0;
+
+no_context:
+	LOGMMCTXP(LOGL_ERROR, mmctx, "No GGSN context found!\n");
+	return gsm48_tx_gsm_act_pdp_rej(mmctx, transaction_id,
+					gsm_cause, 0, NULL);
+}
+
+/* 3GPP TS 24.008 § 9.5.1: Activate PDP Context Request */
+static int gsm48_rx_gsm_act_pdp_req(struct sgsn_mm_ctx *mmctx,
+				    struct msgb *_msg)
+{
+	bool delete = 1;
+	struct msgb *msg;
+	int rc;
+
+	rate_ctr_inc(&sgsn->rate_ctrs->ctr[CTR_PDP_ACTIVATE_REQUEST]);
+
+	/*
+	 * This is painful. We might not have a static GGSN
+	 * configuration and then would need to copy the msg
+	 * and re-do most of this routine (or call it again
+	 * and make sure it only goes through the dynamic
+	 * resolving. The question is what to optimize for
+	 * and the dynamic resolution will be the right thing
+	 * in the long run.
+	 */
+	msg = bssgp_msgb_copy(_msg, __func__);
+	if (!msg) {
+		struct gsm48_hdr *gh = (struct gsm48_hdr *) msgb_gmmh(_msg);
+		uint8_t transaction_id = gsm48_hdr_trans_id(gh);
+
+		LOGMMCTXP(LOGL_ERROR, mmctx, "-> ACTIVATE PDP CONTEXT REQ failed copy.\n");
+		/* Send reject with GSM_CAUSE_INV_MAND_INFO */
+		return gsm48_tx_gsm_act_pdp_rej(mmctx, transaction_id,
+						GSM_CAUSE_NET_FAIL,
+						0, NULL);
+	}
+
+	rc = do_act_pdp_req(mmctx, msg, &delete);
+	if (delete)
+		msgb_free(msg);
+	return rc;
+}
+
+/* 3GPP TS 24.008 § 9.5.8: Deactivate PDP Context Request */
+static int gsm48_rx_gsm_deact_pdp_req(struct sgsn_mm_ctx *mm, struct msgb *msg)
+{
+	struct gsm48_hdr *gh = (struct gsm48_hdr *) msgb_gmmh(msg);
+	uint8_t transaction_id = gsm48_hdr_trans_id(gh);
+	struct sgsn_pdp_ctx *pdp;
+
+	LOGMMCTXP(LOGL_INFO, mm, "-> DEACTIVATE PDP CONTEXT REQ (cause: %s)\n",
+		get_value_string(gsm48_gsm_cause_names, gh->data[0]));
+	rate_ctr_inc(&sgsn->rate_ctrs->ctr[CTR_PDP_UL_DEACTIVATE_REQUEST]);
+
+	pdp = sgsn_pdp_ctx_by_tid(mm, transaction_id);
+	if (!pdp) {
+		LOGMMCTXP(LOGL_NOTICE, mm, "Deactivate PDP Context Request for "
+			"non-existing PDP Context (IMSI=%s, TI=%u)\n",
+			mm->imsi, transaction_id);
+		return _gsm48_tx_gsm_deact_pdp_acc(mm, transaction_id);
+	}
+
+	return sgsn_delete_pdp_ctx(pdp);
+}
+
+/* 3GPP TS 24.008 § 9.5.9: Deactivate PDP Context Accept */
+static int gsm48_rx_gsm_deact_pdp_ack(struct sgsn_mm_ctx *mm, struct msgb *msg)
+{
+	struct gsm48_hdr *gh = (struct gsm48_hdr *) msgb_gmmh(msg);
+	uint8_t transaction_id = gsm48_hdr_trans_id(gh);
+	struct sgsn_pdp_ctx *pdp;
+
+	LOGMMCTXP(LOGL_INFO, mm, "-> DEACTIVATE PDP CONTEXT ACK\n");
+	rate_ctr_inc(&sgsn->rate_ctrs->ctr[CTR_PDP_UL_DEACTIVATE_ACCEPT]);
+
+	pdp = sgsn_pdp_ctx_by_tid(mm, transaction_id);
+	if (!pdp) {
+		LOGMMCTXP(LOGL_NOTICE, mm, "Deactivate PDP Context Accept for "
+			"non-existing PDP Context (IMSI=%s, TI=%u)\n",
+			mm->imsi, transaction_id);
+		return 0;
+	}
+	/* stop timer 3395 */
+	pdpctx_timer_stop(pdp, 3395);
+	if (pdp->ggsn)
+		return sgsn_delete_pdp_ctx(pdp);
+	/* GTP side already detached, freeing */
+	sgsn_pdp_ctx_free(pdp);
+	return 0;
+}
+
+static int gsm48_rx_gsm_status(struct sgsn_mm_ctx *ctx, struct msgb *msg)
+{
+	struct gsm48_hdr *gh = msgb_l3(msg);
+
+	LOGMMCTXP(LOGL_INFO, ctx, "-> GPRS SM STATUS (cause: %s)\n",
+		get_value_string(gsm48_gsm_cause_names, gh->data[0]));
+
+	return 0;
+}
+
+static void pdpctx_timer_cb(void *_pdp)
+{
+	struct sgsn_pdp_ctx *pdp = _pdp;
+
+	pdp->num_T_exp++;
+
+	switch (pdp->T) {
+	case 3395:	/* waiting for PDP CTX DEACT ACK */
+		if (pdp->num_T_exp > T339X_MAX_RETRANS) {
+			LOGPDPCTXP(LOGL_NOTICE, pdp, "T3395 expired > %d times\n", T339X_MAX_RETRANS);
+			pdp->state = PDP_STATE_INACTIVE;
+			if (pdp->ggsn)
+				sgsn_delete_pdp_ctx(pdp);
+			else
+				sgsn_pdp_ctx_free(pdp);
+			break;
+		}
+		_gsm48_tx_gsm_deact_pdp_req(pdp->mm, pdp->ti, GSM_CAUSE_NET_FAIL, true);
+		pdpctx_timer_rearm(pdp, 3395);
+		break;
+	default:
+		LOGPDPCTXP(LOGL_ERROR, pdp, "timer expired in unknown mode %u\n",
+			pdp->T);
+	}
+}
+
+/* GPRS Session Management */
+int gsm0408_rcv_gsm(struct sgsn_mm_ctx *mmctx, struct msgb *msg,
+			   struct gprs_llc_llme *llme)
+{
+	struct gsm48_hdr *gh = (struct gsm48_hdr *) msgb_gmmh(msg);
+	int rc;
+
+	/* MMCTX can be NULL when called */
+
+	if (!mmctx) {
+		LOGGBIUP(llme, msg, LOGL_NOTICE, "Cannot handle SM for unknown MM CTX\n");
+		/* 6.1.3.6 */
+		if (gh->msg_type == GSM48_MT_GSM_STATUS)
+			return 0;
+
+		return gsm0408_gprs_force_reattach_oldmsg(msg, llme);
+	}
+
+	switch (gh->msg_type) {
+	case GSM48_MT_GSM_ACT_PDP_REQ:
+		rc = gsm48_rx_gsm_act_pdp_req(mmctx, msg);
+		break;
+	case GSM48_MT_GSM_DEACT_PDP_REQ:
+		rc = gsm48_rx_gsm_deact_pdp_req(mmctx, msg);
+		break;
+	case GSM48_MT_GSM_DEACT_PDP_ACK:
+		rc = gsm48_rx_gsm_deact_pdp_ack(mmctx, msg);
+		break;
+	case GSM48_MT_GSM_STATUS:
+		rc = gsm48_rx_gsm_status(mmctx, msg);
+		break;
+	case GSM48_MT_GSM_REQ_PDP_ACT_REJ:
+	case GSM48_MT_GSM_ACT_AA_PDP_REQ:
+	case GSM48_MT_GSM_DEACT_AA_PDP_REQ:
+		LOGMMCTXP(LOGL_NOTICE, mmctx, "Unimplemented GSM 04.08 GSM msg type 0x%02x: %s\n",
+			gh->msg_type, osmo_hexdump((uint8_t *)gh, msgb_l3len(msg)));
+		rc = gsm48_tx_sm_status(mmctx, GSM_CAUSE_MSGT_NOTEXIST_NOTIMPL);
+		break;
+	default:
+		LOGMMCTXP(LOGL_NOTICE, mmctx, "Unknown GSM 04.08 GSM msg type 0x%02x: %s\n",
+			gh->msg_type, osmo_hexdump((uint8_t *)gh, msgb_l3len(msg)));
+		rc = gsm48_tx_sm_status(mmctx, GSM_CAUSE_MSGT_NOTEXIST_NOTIMPL);
+		break;
+
+	}
+
+	return rc;
+}