diff --git a/openbsc/src/gsm_04_08_gprs.c b/openbsc/src/gsm_04_08_gprs.c
new file mode 100644
index 0000000..af6a481
--- /dev/null
+++ b/openbsc/src/gsm_04_08_gprs.c
@@ -0,0 +1,716 @@
+/* GSM Mobile Radio Interface Layer 3 messages on the A-bis interface
+ * 3GPP TS 04.08 version 7.21.0 Release 1998 / ETSI TS 100 940 V7.21.0 */
+
+/* (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 <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+#include <netinet/in.h>
+
+#include <openbsc/db.h>
+#include <osmocore/msgb.h>
+#include <osmocore/tlv.h>
+#include <openbsc/debug.h>
+#include <openbsc/gsm_data.h>
+#include <osmocore/gsm_utils.h>
+#include <openbsc/gsm_subscriber.h>
+#include <openbsc/gsm_04_08.h>
+#include <openbsc/gsm_04_08_gprs.h>
+#include <openbsc/paging.h>
+#include <osmocore/signal.h>
+#include <osmocore/talloc.h>
+#include <openbsc/transaction.h>
+#include <openbsc/gprs_llc.h>
+#include <openbsc/gprs_sgsn.h>
+
+/* 10.5.5.14 GPRS MM Cause / Table 10.5.147 */
+struct value_string gmm_cause_names[] = {
+	/* FIXME */
+	{ GMM_CAUSE_SEM_INCORR_MSG, "Semantically incorrect message" },
+	{ GMM_CAUSE_INV_MAND_INFO, "Invalid mandatory information" },
+	{ GMM_CAUSE_MSGT_NOTEXIST_NOTIMPL,
+			"Message type non-existant or not implemented" },
+	{ GMM_CAUSE_MSGT_INCOMP_P_STATE,
+			"Message type not compatible with protocol state" },
+	{ GMM_CAUSE_IE_NOTEXIST_NOTIMPL,
+			"Information element non-existent or not implemented" },
+	{ GMM_CAUSE_COND_IE_ERR, "Conditional IE error" },
+	{ GMM_CAUSE_MSG_INCOMP_P_STATE,
+				"Message not compatible with protocol state " },
+	{ GMM_CAUSE_PROTO_ERR_UNSPEC, "Protocol error, unspecified" },
+	{ 0, NULL }
+};
+
+/* 10.5.6.6 SM Cause / Table 10.5.157 */
+struct value_string gsm_cause_names[] = {
+	{ GSM_CAUSE_INSUFF_RSRC, "Insufficient resources" },
+	{ GSM_CAUSE_MISSING_APN, "Missing or unknown APN" },
+	{ GSM_CAUSE_UNKNOWN_PDP, "Unknown PDP address or PDP type" },
+	{ GSM_CAUSE_AUTH_FAILED, "User Authentication failed" },
+	{ GSM_CAUSE_ACT_REJ_GGSN, "Activation rejected by GGSN" },
+	{ GSM_CAUSE_ACT_REJ_UNSPEC, "Activation rejected, unspecified" },
+	{ GSM_CAUSE_SERV_OPT_NOTSUPP, "Service option not supported" },
+	{ GSM_CAUSE_REQ_SERV_OPT_NOTSUB,
+				"Requested service option not subscribed" },
+	{ GSM_CAUSE_SERV_OPT_TEMP_OOO,
+				"Service option temporarily out of order" },
+	{ GSM_CAUSE_NSAPI_IN_USE, "NSAPI already used" },
+	{ GSM_CAUSE_DEACT_REGULAR, "Regular deactivation" },
+	{ GSM_CAUSE_QOS_NOT_ACCEPTED, "QoS not accepted" },
+	{ GSM_CAUSE_NET_FAIL, "Network Failure" },
+	{ GSM_CAUSE_REACT_RQD, "Reactivation required" },
+	{ GSM_CAUSE_FEATURE_NOTSUPP, "Feature not supported " },
+	{ GSM_CAUSE_INVALID_TRANS_ID, "Invalid transaction identifier" },
+	{ GSM_CAUSE_SEM_INCORR_MSG, "Semantically incorrect message" },
+	{ GSM_CAUSE_INV_MAND_INFO, "Invalid mandatory information" },
+	{ GSM_CAUSE_MSGT_NOTEXIST_NOTIMPL,
+			"Message type non-existant or not implemented" },
+	{ GSM_CAUSE_MSGT_INCOMP_P_STATE,
+			"Message type not compatible with protocol state" },
+	{ GSM_CAUSE_IE_NOTEXIST_NOTIMPL,
+			"Information element non-existent or not implemented" },
+	{ GSM_CAUSE_COND_IE_ERR, "Conditional IE error" },
+	{ GSM_CAUSE_MSG_INCOMP_P_STATE,
+				"Message not compatible with protocol state " },
+	{ GSM_CAUSE_PROTO_ERR_UNSPEC, "Protocol error, unspecified" },
+	{ 0, NULL }
+};
+
+static const char *att_name(u_int8_t type)
+{
+	switch (type) {
+	case GPRS_ATT_T_ATTACH:
+		return "GPRS attach";
+	case GPRS_ATT_T_ATT_WHILE_IMSI:
+		return "GPRS attach while IMSI attached";
+	case GPRS_ATT_T_COMBINED:
+		return "Combined GPRS/IMSI attach";
+	default:
+		return "unknown";
+	}
+}
+
+static const char *upd_name(u_int8_t type)
+{
+	switch (type) {
+	case GPRS_UPD_T_RA:
+		return "RA updating";
+	case GPRS_UPD_T_RA_LA:
+		return "combined RA/LA updating";
+	case GPRS_UPD_T_RA_LA_IMSI_ATT:
+		return "combined RA/LA updating + IMSI attach";
+	case GPRS_UPD_T_PERIODIC:
+		return "periodic updating";
+	}
+	return "unknown";
+}
+
+void gsm48_parse_ra(struct gprs_ra_id *raid, const u_int8_t *buf)
+{
+	raid->mcc = (buf[0] & 0xf) * 100;
+	raid->mcc += (buf[0] >> 4) * 10;
+	raid->mcc += (buf[1] & 0xf) * 1;
+
+	/* I wonder who came up with the stupidity of encoding the MNC
+	 * differently depending on how many digits its decimal number has! */
+	if ((buf[1] >> 4) == 0xf) {
+		raid->mnc = (buf[2] & 0xf) * 10;
+		raid->mnc += (buf[2] >> 4) * 1;
+	} else {
+		raid->mnc = (buf[2] & 0xf) * 100;
+		raid->mnc += (buf[2] >> 4) * 10;
+		raid->mnc += (buf[1] >> 4) * 1;
+	}
+
+	raid->lac = ntohs(*(u_int16_t *)(buf + 3));
+	raid->rac = buf[5];
+}
+
+/* Send a message through the underlying layer */
+static int gsm48_gmm_sendmsg(struct msgb *msg, int command)
+{
+	return gprs_llc_tx_ui(msg, GPRS_SAPI_GMM, command);
+}
+
+/* TS 03.03 Chapter 2.6 */
+int gprs_tlli_type(u_int32_t tlli)
+{
+	if ((tlli & 0xc0000000) == 0xc0000000)
+		return TLLI_LOCAL;
+	else if ((tlli & 0xc0000000) == 0x80000000)
+		return TLLI_FOREIGN;
+	else if ((tlli & 0xf8000000) == 0x78000000)
+		return TLLI_RANDOM;
+	else if ((tlli & 0xf8000000) == 0x70000000)
+		return TLLI_AUXILIARY;
+
+	return TLLI_RESERVED;
+}
+
+/* Chapter 9.4.2: Attach accept */
+static int gsm48_tx_gmm_att_ack(struct msgb *old_msg)
+{
+	struct msgb *msg = gsm48_msgb_alloc();
+	struct gsm48_hdr *gh;
+	struct gsm48_attach_ack *aa;
+
+	DEBUGP(DMM, "<- GPRS ATTACH ACCEPT\n");
+
+	msg->tlli = old_msg->tlli;
+	msg->trx = old_msg->trx;
+
+	gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh));
+	gh->proto_discr = GSM48_PDISC_MM_GPRS;
+	gh->msg_type = GSM48_MT_GMM_ATTACH_ACK;
+
+	aa = (struct gsm48_attach_ack *) msgb_put(msg, sizeof(*aa));
+	aa->force_stby = 0;	/* not indicated */
+	aa->att_result = 1;	/* GPRS only */
+	aa->ra_upd_timer = GPRS_TMR_MINUTE | 10;
+	aa->radio_prio = 4;	/* lowest */
+	gsm48_ra_id_by_bts(aa->ra_id.digits, old_msg->trx->bts);
+
+	/* Option: P-TMSI signature, allocated P-TMSI, MS ID, ... */
+	return gsm48_gmm_sendmsg(msg, 0);
+}
+
+/* Chapter 9.4.5: Attach reject */
+static int gsm48_tx_gmm_att_rej(struct msgb *old_msg, u_int8_t gmm_cause)
+{
+	struct msgb *msg = gsm48_msgb_alloc();
+	struct gsm48_hdr *gh;
+
+	DEBUGP(DMM, "<- GPRS ATTACH REJECT\n");
+
+	msg->tlli = old_msg->tlli;
+	msg->trx = old_msg->trx;
+
+	gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh) + 1);
+	gh->proto_discr = GSM48_PDISC_MM_GPRS;
+	gh->msg_type = GSM48_MT_GMM_ATTACH_REJ;
+	gh->data[0] = gmm_cause;
+
+	return gsm48_gmm_sendmsg(msg, 0);
+}
+
+/* Transmit Chapter 9.4.12 Identity Request */
+static int gsm48_tx_gmm_id_req(struct msgb *old_msg, u_int8_t id_type)
+{
+	struct msgb *msg = gsm48_msgb_alloc();
+	struct gsm48_hdr *gh;
+
+	DEBUGP(DMM, "-> GPRS IDENTITY REQUEST: mi_type=%02x\n", id_type);
+
+	msg->tlli = old_msg->tlli;
+	msg->trx = old_msg->trx;
+
+	gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh) + 1);
+	gh->proto_discr = GSM48_PDISC_MM_GPRS;
+	gh->msg_type = GSM48_MT_GMM_ID_REQ;
+	/* 10.5.5.9 ID type 2 + identity type and 10.5.5.7 'force to standby' IE */
+	gh->data[0] = id_type & 0xf;
+
+	return gsm48_gmm_sendmsg(msg, 0);
+}
+
+/* Check if we can already authorize a subscriber */
+static int gsm48_gmm_authorize(struct sgsn_mm_ctx *ctx, struct msgb *msg)
+{
+	if (strlen(ctx->imei) && strlen(ctx->imsi)) {
+		ctx->mm_state = GMM_REGISTERED_NORMAL;
+		return gsm48_tx_gmm_att_ack(msg);
+	} 
+	if (!strlen(ctx->imei))
+		return gsm48_tx_gmm_id_req(msg, GSM_MI_TYPE_IMEI);
+
+	if (!strlen(ctx->imsi))
+		return gsm48_tx_gmm_id_req(msg, GSM_MI_TYPE_IMSI);
+
+	return 0;
+}
+
+/* Parse Chapter 9.4.13 Identity Response */
+static int gsm48_rx_gmm_id_resp(struct msgb *msg)
+{
+	struct gsm48_hdr *gh = (struct gsm48_hdr *) msg->gmmh;
+	u_int8_t mi_type = gh->data[1] & GSM_MI_TYPE_MASK;
+	char mi_string[GSM48_MI_SIZE];
+	struct gprs_ra_id ra_id;
+	struct sgsn_mm_ctx *ctx;
+
+	gsm48_mi_to_string(mi_string, sizeof(mi_string), &gh->data[1], gh->data[0]);
+	DEBUGP(DMM, "GMM IDENTITY RESPONSE: mi_type=0x%02x MI(%s) ",
+		mi_type, mi_string);
+
+	gprs_ra_id_by_bts(&ra_id, msg->trx->bts);
+	ctx = sgsn_mm_ctx_by_tlli(msg->tlli, &ra_id);
+	if (!ctx) {
+		DEBUGP(DMM, "from unknown TLLI 0x%08x?!?\n", msg->tlli);
+		return -EINVAL;
+	}
+
+	switch (mi_type) {
+	case GSM_MI_TYPE_IMSI:
+		/* we already have a mm context with current TLLI, but no
+		 * P-TMSI / IMSI yet.  What we now need to do is to fill
+		 * this initial context with data from the HLR */
+		strncpy(ctx->imsi, mi_string, sizeof(ctx->imei));
+		break;
+	case GSM_MI_TYPE_IMEI:
+		strncpy(ctx->imei, mi_string, sizeof(ctx->imei));
+		break;
+	case GSM_MI_TYPE_IMEISV:
+		break;
+	}
+
+	DEBUGPC(DMM, "\n");
+	/* Check if we can let the mobile station enter */
+	return gsm48_gmm_authorize(ctx, msg);
+}
+
+static void attach_rej_cb(void *data)
+{
+	struct sgsn_mm_ctx *ctx = data;
+
+	/* FIXME: determine through which BTS/TRX to send this */
+	//gsm48_tx_gmm_att_rej(ctx->tlli, GMM_CAUSE_MS_ID_NOT_DERIVED);
+	ctx->mm_state = GMM_DEREGISTERED;
+	/* FIXME: release the context */
+}
+
+static void schedule_reject(struct sgsn_mm_ctx *ctx)
+{
+	ctx->T = 3370;
+	ctx->timer.cb = attach_rej_cb;
+	ctx->timer.data = ctx;
+	bsc_schedule_timer(&ctx->timer, 6, 0);
+}
+
+/* Section 9.4.1 Attach request */
+static int gsm48_rx_gmm_att_req(struct msgb *msg)
+{
+	struct gsm48_hdr *gh = (struct gsm48_hdr *) msg->gmmh;
+	u_int8_t *cur = gh->data, *msnc, *mi, *old_ra_info;
+	u_int8_t msnc_len, att_type, mi_len, mi_type;
+	u_int16_t drx_par;
+	u_int32_t tmsi;
+	char mi_string[GSM48_MI_SIZE];
+	struct gprs_ra_id ra_id;
+	struct sgsn_mm_ctx *ctx;
+
+	DEBUGP(DMM, "GMM ATTACH REQUEST ");
+
+	/* As per TS 04.08 Chapter 4.7.1.4, the attach request arrives either
+	 * with a foreign TLLI (P-TMSI that was allocated to the MS before),
+	 * or with random TLLI. */
+
+	gprs_ra_id_by_bts(&ra_id, msg->trx->bts);
+
+	/* MS network capability 10.5.5.12 */
+	msnc_len = *cur++;
+	msnc = cur;
+	if (msnc_len > 2)
+		goto err_inval;
+	cur += msnc_len;
+
+	/* aTTACH Type 10.5.5.2 */
+	att_type = *cur++ & 0x0f;
+
+	/* DRX parameter 10.5.5.6 */
+	drx_par = *cur++;
+	drx_par |= *cur++ << 8;
+
+	/* Mobile Identity (P-TMSI or IMSI) 10.5.1.4 */
+	mi_len = *cur++;
+	mi = cur;
+	if (mi_len > 8)
+		goto err_inval;
+	mi_type = *mi & GSM_MI_TYPE_MASK;
+	cur += mi_len;
+
+	gsm48_mi_to_string(mi_string, sizeof(mi_string), mi, mi_len);
+
+	DEBUGPC(DMM, "MI(%s) type=\"%s\" ", mi_string, att_name(att_type));
+
+	/* Old routing area identification 10.5.5.15 */
+	old_ra_info = cur;
+	cur += 6;
+
+	/* MS Radio Access Capability 10.5.5.12a */
+
+	/* Optional: Old P-TMSI Signature, Requested READY timer, TMSI Status */
+
+	switch (mi_type) {
+	case GSM_MI_TYPE_IMSI:
+		/* Try to find MM context based on IMSI */
+		ctx = sgsn_mm_ctx_by_imsi(mi_string);
+		if (!ctx) {
+#if 0
+			return gsm48_tx_gmm_att_rej(msg, GMM_CAUSE_IMSI_UNKNOWN);
+#else
+			/* As a temorary hack, we simply assume that the IMSI exists */
+			ctx = sgsn_mm_ctx_alloc(0, &ra_id);
+			if (!ctx)
+				return gsm48_tx_gmm_att_rej(msg, GMM_CAUSE_NET_FAIL);
+			strncpy(ctx->imsi, mi_string, sizeof(ctx->imsi));
+#endif
+		}
+		/* FIXME: Start some timer */
+		ctx->mm_state = GMM_COMMON_PROC_INIT;
+		ctx->tlli = msg->tlli;
+		break;
+	case GSM_MI_TYPE_TMSI:
+		tmsi = strtoul(mi_string, NULL, 10);
+		/* Try to find MM context based on P-TMSI */
+		ctx = sgsn_mm_ctx_by_ptmsi(tmsi);
+		if (!ctx) {
+			ctx = sgsn_mm_ctx_alloc(msg->tlli, &ra_id);
+			/* FIXME: Start some timer */
+			ctx->mm_state = GMM_COMMON_PROC_INIT;
+			ctx->tlli = msg->tlli;
+		}
+		break;
+	default:
+		break;
+	}
+
+	/* FIXME: allocate a new P-TMSI (+ P-TMSI signature) */
+	/* FIXME: update the TLLI with the new local TLLI based on the P-TMSI */
+
+	DEBUGPC(DMM, "\n");
+
+	return ctx ? gsm48_gmm_authorize(ctx, msg) : 0;
+
+err_inval:
+	DEBUGPC(DMM, "\n");
+	return gsm48_tx_gmm_att_rej(msg, GMM_CAUSE_SEM_INCORR_MSG);
+}
+
+/* Chapter 9.4.15: Routing area update accept */
+static int gsm48_tx_gmm_ra_upd_ack(struct msgb *old_msg)
+{
+	struct msgb *msg = gsm48_msgb_alloc();
+	struct gsm48_hdr *gh;
+	struct gsm48_ra_upd_ack *rua;
+
+	DEBUGP(DMM, "<- ROUTING AREA UPDATE ACCEPT\n");
+
+	msg->tlli = old_msg->tlli;
+	msg->trx = old_msg->trx;
+
+	gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh));
+	gh->proto_discr = GSM48_PDISC_MM_GPRS;
+	gh->msg_type = GSM48_MT_GMM_RA_UPD_ACK;
+
+	rua = (struct gsm48_ra_upd_ack *) msgb_put(msg, sizeof(*rua));
+	rua->force_stby = 0;	/* not indicated */
+	rua->upd_result = 0;	/* RA updated */
+	rua->ra_upd_timer = GPRS_TMR_MINUTE | 10;
+	gsm48_ra_id_by_bts(rua->ra_id.digits, old_msg->trx->bts);
+
+	/* Option: P-TMSI signature, allocated P-TMSI, MS ID, ... */
+	return gsm48_gmm_sendmsg(msg, 0);
+}
+
+/* Chapter 9.4.17: Routing area update reject */
+static int gsm48_tx_gmm_ra_upd_rej(struct msgb *old_msg, u_int8_t cause)
+{
+	struct msgb *msg = gsm48_msgb_alloc();
+	struct gsm48_hdr *gh;
+
+	DEBUGP(DMM, "<- ROUTING AREA UPDATE REJECT\n");
+
+	msg->tlli = old_msg->tlli;
+	msg->trx = old_msg->trx;
+
+	gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh) + 2);
+	gh->proto_discr = GSM48_PDISC_MM_GPRS;
+	gh->msg_type = GSM48_MT_GMM_RA_UPD_REJ;
+	gh->data[0] = cause;
+	gh->data[1] = 0; /* ? */
+
+	/* Option: P-TMSI signature, allocated P-TMSI, MS ID, ... */
+	return gsm48_gmm_sendmsg(msg, 0);
+}
+
+/* Chapter 9.4.14: Routing area update request */
+static int gsm48_rx_gmm_ra_upd_req(struct msgb *msg)
+{
+	struct gsm48_hdr *gh = (struct gsm48_hdr *) msg->gmmh;
+	struct sgsn_mm_ctx *mmctx;
+	u_int8_t *cur = gh->data;
+	struct gprs_ra_id old_ra_id;
+	u_int8_t upd_type;
+
+	/* Update Type 10.5.5.18 */
+	upd_type = *cur++ & 0x0f;
+
+	DEBUGP(DMM, "GMM RA UPDATE REQUEST type=\"%s\" ", upd_name(upd_type));
+
+	/* Old routing area identification 10.5.5.15 */
+	gsm48_parse_ra(&old_ra_id, cur);
+	cur += 6;
+
+	/* MS Radio Access Capability 10.5.5.12a */
+
+	/* Optional: Old P-TMSI Signature, Requested READY timer, TMSI Status,
+	 * DRX parameter, MS network capability */
+
+	switch (upd_type) {
+	case GPRS_UPD_T_RA_LA:
+	case GPRS_UPD_T_RA_LA_IMSI_ATT:
+		DEBUGPC(DMM, " unsupported in Mode III, is your SI13 corrupt?\n");
+		return gsm48_tx_gmm_ra_upd_rej(msg, GMM_CAUSE_PROTO_ERR_UNSPEC);
+		break;
+	case GPRS_UPD_T_RA:
+	case GPRS_UPD_T_PERIODIC:
+		break;
+	}
+
+	/* Look-up the MM context based on old RA-ID and TLLI */
+	mmctx = sgsn_mm_ctx_by_tlli(msg->tlli, &old_ra_id);
+	if (!mmctx || mmctx->mm_state == GMM_DEREGISTERED) {
+		/* The MS has to perform GPRS attach */
+		DEBUGPC(DMM, " REJECT\n");
+		return gsm48_tx_gmm_ra_upd_rej(msg, GMM_CAUSE_IMPL_DETACHED);
+	}
+
+	/* FIXME: Update the MM context with the new RA-ID */
+	/* FIXME: Update the MM context with the new TLLI */
+	/* FIXME: Update the MM context with the MS radio acc capabilities */
+	/* FIXME: Update the MM context with the MS network capabilities */
+
+	DEBUGPC(DMM, " ACCEPT\n");
+	return gsm48_tx_gmm_ra_upd_ack(msg);
+}
+
+static int gsm48_rx_gmm_status(struct msgb *msg)
+{
+	struct gsm48_hdr *gh = msgb_l3(msg);
+
+	DEBUGP(DMM, "GPRS MM STATUS (cause: %s)\n",
+		get_value_string(gmm_cause_names, gh->data[0]));
+
+	return 0;
+}
+
+/* GPRS Mobility Management */
+static int gsm0408_rcv_gmm(struct msgb *msg)
+{
+	struct gsm48_hdr *gh = (struct gsm48_hdr *) msg->gmmh;
+	int rc;
+
+	switch (gh->msg_type) {
+	case GSM48_MT_GMM_RA_UPD_REQ:
+		rc = gsm48_rx_gmm_ra_upd_req(msg);
+		break;
+	case GSM48_MT_GMM_ATTACH_REQ:
+		rc = gsm48_rx_gmm_att_req(msg);
+		break;
+	case GSM48_MT_GMM_ID_RESP:
+		rc = gsm48_rx_gmm_id_resp(msg);
+		break;
+	case GSM48_MT_GMM_STATUS:
+		rc = gsm48_rx_gmm_status(msg);
+		break;
+	case GSM48_MT_GMM_RA_UPD_COMPL:
+		/* only in case SGSN offered new P-TMSI */
+	case GSM48_MT_GMM_ATTACH_COMPL:
+		/* only in case SGSN offered new P-TMSI */
+	case GSM48_MT_GMM_DETACH_REQ:
+	case GSM48_MT_GMM_PTMSI_REALL_COMPL:
+	case GSM48_MT_GMM_AUTH_CIPH_RESP:
+		DEBUGP(DMM, "Unimplemented GSM 04.08 GMM msg type 0x%02x\n",
+			gh->msg_type);
+		break;
+	default:
+		DEBUGP(DMM, "Unknown GSM 04.08 GMM msg type 0x%02x\n",
+			gh->msg_type);
+		break;
+	}
+
+	return rc;
+}
+
+/* Section 9.5.2: Ativate PDP Context Accept */
+static int gsm48_tx_gsm_act_pdp_acc(struct msgb *old_msg, struct gsm48_act_pdp_ctx_req *req)
+{
+	struct gsm48_hdr *old_gh = (struct gsm48_hdr *) old_msg->gmmh;
+	struct msgb *msg = gsm48_msgb_alloc();
+	struct gsm48_act_pdp_ctx_ack *act_ack;
+	struct gsm48_hdr *gh;
+	u_int8_t transaction_id = ((old_gh->proto_discr >> 4) ^ 0x8); /* flip */
+
+	DEBUGP(DMM, "<- ACTIVATE PDP CONTEXT ACK\n");
+
+	msg->tlli = old_msg->tlli;
+	msg->trx = old_msg->trx;
+
+	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;
+	act_ack = (struct gsm48_act_pdp_ctx_ack *)
+					msgb_put(msg, sizeof(*act_ack));
+	act_ack->llc_sapi = req->req_llc_sapi;
+	memcpy(act_ack->qos_lv, req->req_qos_lv, sizeof(act_ack->qos_lv));
+	//act_ack->radio_prio = 4;
+
+	return gsm48_gmm_sendmsg(msg, 0);
+}
+
+/* Section 9.5.9: Deactivate PDP Context Accept */
+static int gsm48_tx_gsm_deact_pdp_acc(struct msgb *old_msg)
+{
+	struct gsm48_hdr *old_gh = (struct gsm48_hdr *) old_msg->gmmh;
+	struct msgb *msg = gsm48_msgb_alloc();
+	struct gsm48_hdr *gh;
+	u_int8_t transaction_id = ((old_gh->proto_discr >> 4) ^ 0x8); /* flip */
+
+	DEBUGP(DMM, "<- DEACTIVATE PDP CONTEXT ACK\n");
+
+	msg->tlli = old_msg->tlli;
+	msg->trx = old_msg->trx;
+
+	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);
+}
+
+/* Section 9.5.1: Activate PDP Context Request */
+static int gsm48_rx_gsm_act_pdp_req(struct msgb *msg)
+{
+	struct gsm48_hdr *gh = (struct gsm48_hdr *) msg->gmmh;
+	struct gsm48_act_pdp_ctx_req *act_req = (struct gsm48_act_pdp_ctx_req *) gh->data;
+	u_int8_t *pdp_addr_lv = act_req->data;
+
+	DEBUGP(DMM, "ACTIVATE PDP CONTEXT REQ\n");
+
+	/* FIXME: parse access point name + IPCP config options */
+
+	return gsm48_tx_gsm_act_pdp_acc(msg, act_req);
+}
+
+/* Section 9.5.8: Deactivate PDP Context Request */
+static int gsm48_rx_gsm_deact_pdp_req(struct msgb *msg)
+{
+	struct gsm48_hdr *gh = (struct gsm48_hdr *) msg->gmmh;
+
+	DEBUGP(DMM, "DEACTIVATE PDP CONTEXT REQ (cause: %s)\n",
+		get_value_string(gsm_cause_names, gh->data[0]));
+
+	return gsm48_tx_gsm_deact_pdp_acc(msg);
+}
+
+static int gsm48_rx_gsm_status(struct msgb *msg)
+{
+	struct gsm48_hdr *gh = msgb_l3(msg);
+
+	DEBUGP(DMM, "GPRS SM STATUS (cause: %s)\n",
+		get_value_string(gsm_cause_names, gh->data[0]));
+
+	return 0;
+}
+
+/* GPRS Session Management */
+static int gsm0408_rcv_gsm(struct msgb *msg)
+{
+	struct gsm48_hdr *gh = (struct gsm48_hdr *) msg->gmmh;
+	int rc;
+
+	switch (gh->msg_type) {
+	case GSM48_MT_GSM_ACT_PDP_REQ:
+		rc = gsm48_rx_gsm_act_pdp_req(msg);
+		break;
+	case GSM48_MT_GSM_DEACT_PDP_REQ:
+		rc = gsm48_rx_gsm_deact_pdp_req(msg);
+	case GSM48_MT_GSM_STATUS:
+		rc = gsm48_rx_gsm_status(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:
+		DEBUGP(DMM, "Unimplemented GSM 04.08 GSM msg type 0x%02x\n",
+			gh->msg_type);
+		break;
+	default:
+		DEBUGP(DMM, "Unknown GSM 04.08 GSM msg type 0x%02x\n",
+			gh->msg_type);
+		break;
+
+	}
+
+	return rc;
+}
+
+/* Main entry point for incoming 04.08 GPRS messages */
+int gsm0408_gprs_rcvmsg(struct msgb *msg)
+{
+	struct gsm48_hdr *gh = (struct gsm48_hdr *) msg->gmmh;
+	u_int8_t pdisc = gh->proto_discr & 0x0f;
+	int rc = -EINVAL;
+
+	switch (pdisc) {
+	case GSM48_PDISC_MM_GPRS:
+		rc = gsm0408_rcv_gmm(msg);
+		break;
+	case GSM48_PDISC_SM_GPRS:
+		rc = gsm0408_rcv_gsm(msg);
+		break;
+	default:
+		DEBUGP(DMM, "Unknown GSM 04.08 discriminator 0x%02x\n",
+			pdisc);
+		break;
+	}
+
+	return rc;
+}
+
+/* Determine the 'struct gsm_bts' from a RA ID */
+struct gsm_bts *gsm48_bts_by_ra_id(struct gsm_network *net,
+				   const u_int8_t *buf, unsigned int len)
+{
+	struct gprs_ra_id raid;
+	struct gsm_bts *bts;
+
+	if (len < 6)
+		return NULL;
+
+	gsm48_parse_ra(&raid, buf);
+
+	if (net->country_code != raid.mcc ||
+	    net->network_code != raid.mnc)
+		return NULL;
+
+	llist_for_each_entry(bts, &net->bts_list, list) {
+		/* FIXME: we actually also need to check the
+		 * routing area code! */
+		if (bts->location_area_code == raid.lac)
+			return bts;
+	}
+
+	return NULL;
+}
+