diff --git a/include/re_sipreg.h b/include/re_sipreg.h
index a0c1bae8c..a8b949ca4 100644
--- a/include/re_sipreg.h
+++ b/include/re_sipreg.h
@@ -15,4 +15,6 @@ int sipreg_register(struct sipreg **regp, struct sip *sip, const char *reg_uri,
 		    sip_resp_h *resph, void *arg,
 		    const char *params, const char *fmt, ...);
 
+int sipreg_set_rwait(struct sipreg *reg, uint32_t rwait);
+
 const struct sa *sipreg_laddr(const struct sipreg *reg);
diff --git a/src/sipreg/reg.c b/src/sipreg/reg.c
index 3967200f0..0375d1892 100644
--- a/src/sipreg/reg.c
+++ b/src/sipreg/reg.c
@@ -39,6 +39,7 @@ struct sipreg {
 	void *arg;
 	uint32_t expires;
 	uint32_t failc;
+	uint32_t rwait;
 	uint32_t wait;
 	enum sip_transp tp;
 	bool registered;
@@ -188,7 +189,7 @@ static void response_handler(int err, const struct sip_msg *msg, void *arg)
 		reg->wait = reg->expires;
 		sip_msg_hdr_apply(msg, true, SIP_HDR_CONTACT, contact_handler,
 				  reg);
-		reg->wait *= 900;
+		reg->wait *= reg->rwait * (1000 / 100);
 		reg->failc = 0;
 
 		if (reg->regid > 0 && !reg->terminated && !reg->ka)
@@ -308,7 +309,7 @@ static int request(struct sipreg *reg, bool reset_ls)
  * @param to_uri   SIP To-header URI
  * @param from_name  SIP From-header display name (optional)
  * @param from_uri SIP From-header URI
- * @param expires  Registration interval in [seconds]
+ * @param expires  Registration expiry time in [seconds]
  * @param cuser    Contact username
  * @param routev   Optional route vector
  * @param routec   Number of routes
@@ -378,6 +379,7 @@ int sipreg_register(struct sipreg **regp, struct sip *sip, const char *reg_uri,
 
 	reg->sip     = mem_ref(sip);
 	reg->expires = expires;
+	reg->rwait   = 90;
 	reg->resph   = resph ? resph : dummy_handler;
 	reg->arg     = arg;
 	reg->regid   = regid;
@@ -396,6 +398,25 @@ int sipreg_register(struct sipreg **regp, struct sip *sip, const char *reg_uri,
 }
 
 
+/**
+ * Set the relative registration interval in percent from proxy expiry time. A
+ * value from 5-95% is accepted.
+ *
+ * @param reg   SIP Registration client
+ * @param rwait The relative registration interval in [%].
+ *
+ * @return 0 if success, otherwise errorcode
+ */
+int sipreg_set_rwait(struct sipreg *reg, uint32_t rwait)
+{
+	if (!reg || rwait < 5 || rwait > 95)
+		return EINVAL;
+
+	reg->rwait = rwait;
+	return 0;
+}
+
+
 /**
  * Get the local socket address for a SIP Registration client
  *