diff --git a/openbsc/src/gprs/Makefile.am b/openbsc/src/gprs/Makefile.am
index 049d41d..87dbc30 100644
--- a/openbsc/src/gprs/Makefile.am
+++ b/openbsc/src/gprs/Makefile.am
@@ -13,7 +13,8 @@
 bin_PROGRAMS = osmo-gbproxy
 endif
 
-osmo_gbproxy_SOURCES = gb_proxy.c gb_proxy_main.c gb_proxy_vty.c
+osmo_gbproxy_SOURCES =  gb_proxy.c gb_proxy_main.c gb_proxy_vty.c \
+			gprs_llc_parse.c crc24.c
 osmo_gbproxy_LDADD = 	$(top_builddir)/src/libcommon/libcommon.a \
 			$(OSMO_LIBS)
 
diff --git a/openbsc/src/gprs/gb_proxy.c b/openbsc/src/gprs/gb_proxy.c
index 9de2ca9..82e9e8c 100644
--- a/openbsc/src/gprs/gb_proxy.c
+++ b/openbsc/src/gprs/gb_proxy.c
@@ -43,6 +43,10 @@
 #include <openbsc/debug.h>
 #include <openbsc/gb_proxy.h>
 
+#include <openbsc/gprs_llc.h>
+#include <openbsc/gsm_04_08.h>
+#include <openbsc/gsm_04_08_gprs.h>
+
 enum gbprox_global_ctr {
 	GBPROX_GLOB_CTR_INV_BVCI,
 	GBPROX_GLOB_CTR_INV_LAI,
@@ -55,6 +59,9 @@
 	GBPROX_GLOB_CTR_RESTART_RESET_SGSN,
 	GBPROX_GLOB_CTR_TX_ERR_SGSN,
 	GBPROX_GLOB_CTR_OTHER_ERR,
+	GBPROX_GLOB_CTR_RAID_PATCHED_BSS,
+	GBPROX_GLOB_CTR_RAID_PATCHED_SGSN,
+	GBPROX_GLOB_CTR_PATCH_ERR,
 };
 
 static const struct rate_ctr_desc global_ctr_description[] = {
@@ -69,6 +76,9 @@
 	{ "restart.sgsn",   "Restarted RESET procedure (SGSN)" },
 	{ "tx-err.sgsn",    "NS Transmission error     (SGSN)" },
 	{ "error",          "Other error                     " },
+	{ "raid-mod.bss",   "RAID patched              (BSS )" },
+	{ "raid-mod.sgsn",  "RAID patched              (SGSN)" },
+	{ "mod-err",        "Patching error                  " },
 };
 
 static const struct rate_ctr_group_desc global_ctrg_desc = {
@@ -112,6 +122,11 @@
 	.ctr_desc = peer_ctr_description,
 };
 
+static struct gbprox_patch_state {
+	int local_mnc;
+	int local_mcc;
+} gbprox_patch_state = {0};
+
 struct gbprox_peer {
 	struct llist_head list;
 
@@ -260,6 +275,118 @@
 	msgb_pull(msg, strip_len);
 }
 
+/* patch RA identifier in place, update peer accordingly */
+static void gbprox_patch_raid(uint8_t *raid_enc, struct gbprox_patch_state *state,
+			      int to_bss, const char *log_text)
+{
+	const int old_local_mcc = state->local_mcc;
+	const int old_local_mnc = state->local_mnc;
+	int old_mcc;
+	int old_mnc;
+	struct gprs_ra_id raid;
+
+	gsm48_parse_ra(&raid, raid_enc);
+
+	old_mcc = raid.mcc;
+	old_mnc = raid.mnc;
+
+	if (!to_bss) {
+		/* BSS -> SGSN */
+		/* save BSS side MCC/MNC */
+		if (!gbcfg.core_mcc || raid.mcc == gbcfg.core_mcc) {
+			state->local_mcc = 0;
+		} else {
+			state->local_mcc = raid.mcc;
+			raid.mcc = gbcfg.core_mcc;
+		}
+
+		if (!gbcfg.core_mnc || raid.mnc == gbcfg.core_mnc) {
+			state->local_mnc = 0;
+		} else {
+			state->local_mnc = raid.mnc;
+			raid.mnc = gbcfg.core_mnc;
+		}
+	} else {
+		/* SGSN -> BSS */
+		if (state->local_mcc)
+			raid.mcc = state->local_mcc;
+
+		if (state->local_mnc)
+			raid.mnc = state->local_mnc;
+	}
+
+	if (old_local_mcc != state->local_mcc ||
+	    old_local_mnc != state->local_mnc)
+		LOGP(DGPRS, LOGL_NOTICE,
+		     "Patching RAID %sactivated, msg: %s, "
+		     "local: %d-%d, core: %d-%d, to %s\n",
+		     state->local_mcc || state->local_mnc ?
+		     "" : "de",
+		     log_text,
+		     state->local_mcc, state->local_mnc,
+		     gbcfg.core_mcc, gbcfg.core_mnc,
+		     to_bss ? "BSS" : "SGSN");
+
+	if (state->local_mcc || state->local_mnc) {
+		enum gbprox_global_ctr counter =
+			to_bss ?
+			GBPROX_GLOB_CTR_RAID_PATCHED_SGSN :
+			GBPROX_GLOB_CTR_RAID_PATCHED_BSS;
+
+		LOGP(DGPRS, LOGL_DEBUG,
+		       "Patching %s to %s: "
+		       "%d-%d-%d-%d -> %d-%d-%d-%d\n",
+		       log_text,
+		       to_bss ? "BSS" : "SGSN",
+		       old_mcc, old_mnc, raid.lac, raid.rac,
+		       raid.mcc, raid.mnc, raid.lac, raid.rac);
+
+		gsm48_construct_ra(raid_enc, &raid);
+		rate_ctr_inc(&get_global_ctrg()->ctr[counter]);
+	}
+}
+
+/* patch BSSGP message to use core_mcc/mnc on the SGSN side */
+static void gbprox_patch_bssgp_message(struct msgb *msg, int to_bss)
+{
+	struct bssgp_normal_hdr *bgph;
+	struct bssgp_ud_hdr *budh;
+	struct tlv_parsed tp;
+	uint8_t pdu_type;
+	struct gbprox_patch_state *state = &gbprox_patch_state;
+	uint8_t *data;
+	size_t data_len;
+
+	if (!gbcfg.core_mcc && !gbcfg.core_mnc)
+		return;
+
+	bgph = (struct bssgp_normal_hdr *) msgb_bssgph(msg);
+	budh = (struct bssgp_ud_hdr *) msgb_bssgph(msg);
+	pdu_type = bgph->pdu_type;
+
+	if (to_bss && !state->local_mcc && !state->local_mnc)
+		return;
+
+	if (pdu_type == BSSGP_PDUT_UL_UNITDATA ||
+	    pdu_type == BSSGP_PDUT_DL_UNITDATA) {
+		data = budh->data;
+		data_len = msgb_bssgp_len(msg) - sizeof(*budh);
+	} else {
+		data = bgph->data;
+		data_len = msgb_bssgp_len(msg) - sizeof(*bgph);
+	}
+
+	bssgp_tlv_parse(&tp, data, data_len);
+
+	if (TLVP_PRESENT(&tp, BSSGP_IE_ROUTEING_AREA))
+		gbprox_patch_raid((uint8_t *)TLVP_VAL(&tp, BSSGP_IE_ROUTEING_AREA),
+				  state, to_bss, "ROUTING_AREA");
+
+	if (TLVP_PRESENT(&tp, BSSGP_IE_CELL_ID))
+		gbprox_patch_raid((uint8_t *)TLVP_VAL(&tp, BSSGP_IE_CELL_ID),
+				  state, to_bss, "CELL_ID");
+}
+
 /* feed a message down the NS-VC associated with the specified peer */
 static int gbprox_relay2sgsn(struct msgb *old_msg, uint16_t ns_bvci)
 {
@@ -276,6 +403,8 @@
 
 	strip_ns_hdr(msg);
 
+	gbprox_patch_bssgp_message(msg, 0);
+
 	rc = gprs_ns_sendmsg(bssgp_nsi, msg);
 	if (rc < 0)
 		rate_ctr_inc(&get_global_ctrg()->ctr[GBPROX_GLOB_CTR_TX_ERR_SGSN]);
@@ -679,6 +808,9 @@
 	struct gbprox_peer *peer;
 	int remote_end_is_sgsn = nsei == gbcfg.nsip_sgsn_nsei;
 
+	if (remote_end_is_sgsn)
+		gbprox_patch_bssgp_message(msg, 1);
+
 	/* Only BVCI=0 messages need special treatment */
 	if (ns_bvci == 0 || ns_bvci == 1) {
 		if (remote_end_is_sgsn)
diff --git a/openbsc/src/gprs/gb_proxy_main.c b/openbsc/src/gprs/gb_proxy_main.c
index ff2e14b..1f140d4 100644
--- a/openbsc/src/gprs/gb_proxy_main.c
+++ b/openbsc/src/gprs/gb_proxy_main.c
@@ -66,7 +66,7 @@
 	"There is NO WARRANTY, to the extent permitted by law.\r\n";
 
 static char *config_file = "osmo_gbproxy.cfg";
-struct gbproxy_config gbcfg;
+struct gbproxy_config gbcfg = {0};
 static int daemonize = 0;
 
 /* Pointer to the SGSN peer */
diff --git a/openbsc/src/gprs/gb_proxy_vty.c b/openbsc/src/gprs/gb_proxy_vty.c
index 2de0d3b..04431f0 100644
--- a/openbsc/src/gprs/gb_proxy_vty.c
+++ b/openbsc/src/gprs/gb_proxy_vty.c
@@ -51,6 +51,13 @@
 	vty_out(vty, " sgsn nsei %u%s", g_cfg->nsip_sgsn_nsei,
 		VTY_NEWLINE);
 
+	if (g_cfg->core_mcc > 0)
+		vty_out(vty, " core-mobile-country-code %d%s",
+			g_cfg->core_mcc, VTY_NEWLINE);
+	if (g_cfg->core_mnc > 0)
+		vty_out(vty, " core-mobile-network-code %d%s",
+			g_cfg->core_mnc, VTY_NEWLINE);
+
 	return CMD_SUCCESS;
 }
 
@@ -76,6 +83,47 @@
 	return CMD_SUCCESS;
 }
 
+#define GBPROXY_CORE_MNC_STR "Use this network code for the core network\n"
+
+DEFUN(cfg_gbproxy_core_mnc,
+      cfg_gbproxy_core_mnc_cmd,
+      "core-mobile-network-code <1-999>",
+      GBPROXY_CORE_MNC_STR "NCC value\n")
+{
+	g_cfg->core_mnc = atoi(argv[0]);
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gbproxy_no_core_mnc,
+      cfg_gbproxy_no_core_mnc_cmd,
+      "no core-mobile-network-code",
+      NO_STR GBPROXY_CORE_MNC_STR)
+{
+	g_cfg->core_mnc = 0;
+	return CMD_SUCCESS;
+}
+
+#define GBPROXY_CORE_MCC_STR "Use this country code for the core network\n"
+
+DEFUN(cfg_gbproxy_core_mcc,
+      cfg_gbproxy_core_mcc_cmd,
+      "core-mobile-country-code <1-999>",
+      GBPROXY_CORE_MCC_STR "MCC value\n")
+{
+	g_cfg->core_mcc = atoi(argv[0]);
+	return CMD_SUCCESS;
+}
+
+DEFUN(cfg_gbproxy_no_core_mcc,
+      cfg_gbproxy_no_core_mcc_cmd,
+      "no core-mobile-country-code",
+      NO_STR GBPROXY_CORE_MCC_STR)
+{
+	g_cfg->core_mcc = 0;
+	return CMD_SUCCESS;
+}
+
+
 int gbproxy_vty_init(void)
 {
 	install_element_ve(&show_gbproxy_cmd);
@@ -87,6 +135,10 @@
 	install_node(&gbproxy_node, config_write_gbproxy);
 	vty_install_default(GBPROXY_NODE);
 	install_element(GBPROXY_NODE, &cfg_nsip_sgsn_nsei_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_core_mcc_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_core_mnc_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_no_core_mcc_cmd);
+	install_element(GBPROXY_NODE, &cfg_gbproxy_no_core_mnc_cmd);
 
 	return 0;
 }