diff --git a/asterisk/IMS_ConnectionHandler.ttcn b/asterisk/IMS_ConnectionHandler.ttcn
index d1e3185..0d11922 100644
--- a/asterisk/IMS_ConnectionHandler.ttcn
+++ b/asterisk/IMS_ConnectionHandler.ttcn
@@ -66,6 +66,8 @@
 	charstring user,
 	charstring display_name,
 	charstring password,
+	/* Expected User-Location-Info in P-Access-Network-Info */
+	charstring uli_str,
 	octetstring rand,
 	octetstring autn,
 	charstring ipsec_auth_key,
@@ -148,6 +150,7 @@
 	user := user,
 	display_name := f_sip_str_quote(display_name),
 	password := password,
+	uli_str := "2380100010000101",
 	/* The Nonce field is the Base64 encoded version of the RAND value and concatenated with the AUTN: */
 	rand := '14987631f65f8e3788a0798b6ebcd08e'O,
 	autn := 'f6e19a7ccb028000a06b19c9544516e5'O,
@@ -272,6 +275,37 @@
 be indicated by adding a “video” media feature tag to the contact: header." */
 }
 
+/* Validate P-Access-Network-Info: RFC7315 6.4 */
+private function f_ims_validate_register_P_Access_Network_info(PDU_SIP_Request req,
+							       boolean exp_present := true) runs on IMS_ConnHdlr
+
+{
+	if (not exp_present) {
+		if (ispresent(g_rx_sip_req.msgHeader.p_access_network_info)) {
+			Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,
+						log2str(g_name & ": Received unexpected [rfc7315 6.4] P-Access-Info := ",
+						g_rx_sip_req.msgHeader.p_access_network_info));
+		}
+		return;
+	}
+
+	/* exp_present: */
+	var template (present) P_Access_Network_Info expl_tmpl :=
+		tr_P_Access_Network_Info({ tr_Access_net_spec_EUTRAN(g_pars.uli_str) });
+
+	if (not ispresent(g_rx_sip_req.msgHeader.p_access_network_info)) {
+		Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,
+					log2str(g_name & ": Received no P-Access-Info vs exp := ",
+					expl_tmpl));
+	}
+	if (not match(g_rx_sip_req.msgHeader.p_access_network_info, expl_tmpl)) {
+				Misc_Helpers.f_shutdown(__BFILE__, __LINE__, fail,
+							log2str(g_name & ": Received unexpected P-Access-Info := ",
+							g_rx_sip_req.msgHeader.p_access_network_info,
+							"\nvs exp := ", expl_tmpl));
+	}
+}
+
 private function f_ims_parse_security_client(Security_client security_client) runs on IMS_ConnHdlr
 {
 	var boolean found := false;
@@ -390,6 +424,16 @@
 		contact := g_rx_sip_req.msgHeader.contact;
 		f_ims_validate_register_contact(contact);
 
+		/* Validate P-Access-Network-Info: rfc7315 6.4:
+		 * "3GPP will use the P-Access-Network-Info header field to
+		 * carry relatively sensitive information like the cell ID.  Therefore,
+		 * the information MUST NOT be sent outside of the 3GPP domain.""
+		 * [...] "the sensitive information carried in the
+		 * P-Access-Network-Info header field MUST NOT be sent in any initial
+		 * unauthenticated and unprotected requests (e.g., REGISTER)."
+		 */
+		f_ims_validate_register_P_Access_Network_info(g_rx_sip_req, exp_present := false);
+
 		/* TODO: Validate "Expires" is 600000 */
 
 		/* Tx 100 Tyring */
@@ -490,6 +534,9 @@
 					userAgent := omit);
 		SIP.send(tx_resp);
 
+		/* Validate P-Access-Network-Info: */
+		f_ims_validate_register_P_Access_Network_info(g_rx_sip_req, exp_present := true);
+
 		/* Tx 200 OK */
 		to_addr.params := f_sip_param_set(to_addr.params, "tag", f_sip_rand_tag());
 		tx_resp := ts_SIP_Response(sip_call_id,