diff --git a/modules/registrar/save.c b/modules/registrar/save.c
index 6e433bba3e1..b856a4af162 100644
--- a/modules/registrar/save.c
+++ b/modules/registrar/save.c
@@ -444,7 +444,7 @@ static inline int update_contacts(struct sip_msg* _m, urecord_t* _r,
 
 			/* pack the contact_info */
 			if ( (ci=pack_ci( 0, _c, e, 0, ul.nat_flag, _sctx->flags,
-							&_sctx->ownership_tag, NULL))==0 ) {
+							&_sctx->ownership_tag, &_sctx->cmatch))==0 ) {
 				LM_ERR("failed to extract contact info\n");
 				goto error;
 			}
@@ -511,7 +511,7 @@ static inline int update_contacts(struct sip_msg* _m, urecord_t* _r,
 
 				/* pack the contact specific info */
 				if ( (ci=pack_ci( 0, _c, e, 0, ul.nat_flag, _sctx->flags,
-								&_sctx->ownership_tag, NULL))==0 ) {
+								&_sctx->ownership_tag, &_sctx->cmatch))==0 ) {
 					LM_ERR("failed to pack contact specific info\n");
 					goto error;
 				}
diff --git a/modules/usrloc/urecord.c b/modules/usrloc/urecord.c
index 9534c59ee75..7dc5afd9d8f 100644
--- a/modules/usrloc/urecord.c
+++ b/modules/usrloc/urecord.c
@@ -990,6 +990,9 @@ static inline struct ucontact* contact_params_match(ucontact_t* contacts,
 		}
 
 		for (param = _params; param; param = param->next) {
+			/* a bit counter-intuitive, but, according to RFC 3261 § 19.1.4, if
+			 * an unknown URI parameter is missing from either URI,
+			 * the matching of that parameter is successful! */
 			if (get_uri_param_val(&ct, &param->s, &v1) != 0 ||
 			        get_uri_param_val(&cti, &param->s, &v2) != 0)
 				continue;
diff --git a/parser/parse_uri.h b/parser/parse_uri.h
index 3c8f8516953..2f234968b37 100644
--- a/parser/parse_uri.h
+++ b/parser/parse_uri.h
@@ -111,7 +111,10 @@ static inline unsigned short get_uri_port(struct sip_uri* _uri,
  * @param - URI param name to search for
  * @val - output value
  *
- * Return: 0 on parser-recognized parameters or success, -1 otherwise
+ * Return:
+ *   0 on RFC-recognized parameters (even if they are missing!)
+ *       or successful search of unknown ones
+ *  -1 otherwise
  */
 static inline int get_uri_param_val(const struct sip_uri *uri,
                                     const str *param, str *val)