diff --git a/include/osmocom/gsm/gsm0502.h b/include/osmocom/gsm/gsm0502.h
index de92c63..46b629e 100644
--- a/include/osmocom/gsm/gsm0502.h
+++ b/include/osmocom/gsm/gsm0502.h
@@ -32,4 +32,7 @@
 	return (imsi % 1000) % (bs_cc_chans * n_pag_blocks) % n_pag_blocks;
 }
 
+unsigned int
+gsm0502_calc_paging_group(struct gsm48_control_channel_descr *chan_desc, uint64_t imsi);
+
 #endif
diff --git a/include/osmocom/gsm/rsl.h b/include/osmocom/gsm/rsl.h
index 2eb045f..44ded1b 100644
--- a/include/osmocom/gsm/rsl.h
+++ b/include/osmocom/gsm/rsl.h
@@ -3,6 +3,7 @@
 
 #include <stdint.h>
 #include <osmocom/core/utils.h>
+#include <osmocom/core/msgb.h>
 #include <osmocom/gsm/protocol/gsm_08_58.h>
 
 void rsl_init_rll_hdr(struct abis_rsl_rll_hdr *dh, uint8_t msg_type);
diff --git a/src/gsm/Makefile.am b/src/gsm/Makefile.am
index 55b772f..7489327 100644
--- a/src/gsm/Makefile.am
+++ b/src/gsm/Makefile.am
@@ -9,6 +9,6 @@
 
 libosmogsm_la_SOURCES = a5.c rxlev_stat.c tlv_parser.c comp128.c gsm_utils.c \
                         rsl.c gsm48.c gsm48_ie.c gsm0808.c sysinfo.c \
-			gprs_cipher_core.c gsm0480.c abis_nm.c
+			gprs_cipher_core.c gsm0480.c abis_nm.c gsm0502.c
 libosmogsm_la_LDFLAGS = -version-info $(LIBVERSION)
 libosmogsm_la_LIBADD = $(top_builddir)/src/libosmocore.la
diff --git a/src/gsm/gsm0502.c b/src/gsm/gsm0502.c
new file mode 100644
index 0000000..df1d8e9
--- /dev/null
+++ b/src/gsm/gsm0502.c
@@ -0,0 +1,43 @@
+/* Paging helper code */
+
+/* (C) 2009 by Holger Hans Peter Freyther <zecke@selfish.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, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <stdint.h>
+
+#include <osmocom/gsm/protocol/gsm_04_08.h>
+#include <osmocom/gsm/gsm0502.h>
+#include <osmocom/gsm/gsm48.h>
+#include <osmocom/gsm/rsl.h>
+
+unsigned int
+gsm0502_calc_paging_group(struct gsm48_control_channel_descr *chan_desc, uint64_t imsi)
+{
+	int ccch_conf;
+	int bs_cc_chans;
+	int blocks;
+	unsigned int group;
+
+	ccch_conf = chan_desc->ccch_conf;
+	bs_cc_chans = rsl_ccch_conf_to_bs_cc_chans(ccch_conf);
+	/* code word + 2, as 2 channels equals 0x0 */
+	blocks = gsm48_number_of_paging_subchannels(chan_desc);
+	group = gsm0502_get_paging_group(imsi, bs_cc_chans, blocks);
+
+	return group;
+}