diff --git a/CHANGES b/CHANGES
index d84bcf2f03..9945efc2f1 100644
--- a/CHANGES
+++ b/CHANGES
@@ -27,6 +27,9 @@ chan_pjsip
    to the request URI and From URI if the user is determined to be a phone number.
  * New 'moh_passthrough' endpoint setting. This will pass hold and unhold requests
    through using SIP re-invites with sendonly and sendrecv accordingly.
+ * Added the pjsip.conf system type disable_tcp_switch option.  The option
+   allows the user to disable switching from UDP to TCP transports described
+   by RFC 3261 section 18.1.1.
 
 Functions
 ------------------
diff --git a/configs/samples/pjsip.conf.sample b/configs/samples/pjsip.conf.sample
index 017aa59129..06b3bb404e 100644
--- a/configs/samples/pjsip.conf.sample
+++ b/configs/samples/pjsip.conf.sample
@@ -830,6 +830,10 @@
                                 ; should be disposed of (default: "60")
 ;threadpool_max_size=0  ; Maximum number of threads in the res_pjsip threadpool
                         ; A value of 0 indicates no maximum (default: "0")
+;disable_tcp_switch=no  ; Disable automatic switching from UDP to TCP transports
+                        ; if outgoing request is too large.
+                        ; See RFC 3261 section 18.1.1.
+                        ; (default: "no")
 ;type=  ; Must be of type system (default: "")
 
 ;==========================GLOBAL SECTION OPTIONS=========================
diff --git a/res/res_pjsip.c b/res/res_pjsip.c
index dcf771bb33..853f351f93 100644
--- a/res/res_pjsip.c
+++ b/res/res_pjsip.c
@@ -1143,6 +1143,13 @@
 					<synopsis>Maximum number of threads in the res_pjsip threadpool.
 					A value of 0 indicates no maximum.</synopsis>
 				</configOption>
+				<configOption name="disable_tcp_switch" default="no">
+					<synopsis>Disable automatic switching from UDP to TCP transports.</synopsis>
+					<description><para>
+						Disable automatic switching from UDP to TCP transports if outgoing
+						request is too large.  See RFC 3261 section 18.1.1.
+					</para></description>
+				</configOption>
 				<configOption name="type">
 					<synopsis>Must be of type 'system'.</synopsis>
 				</configOption>
diff --git a/res/res_pjsip/config_system.c b/res/res_pjsip/config_system.c
index 7f8da85978..4d0ab467b5 100644
--- a/res/res_pjsip/config_system.c
+++ b/res/res_pjsip/config_system.c
@@ -49,6 +49,8 @@ struct system_config {
 		/*! Maxumum number of threads in the threadpool */
 		int max_size;
 	} threadpool;
+	/*! Nonzero to disable switching from UDP to TCP transport */
+	unsigned int disable_tcp_switch;
 };
 
 static struct ast_threadpool_options sip_threadpool_options = {
@@ -95,6 +97,7 @@ static int system_apply(const struct ast_sorcery *system_sorcery, void *obj)
 
 	if (system->compactheaders) {
 		extern pj_bool_t pjsip_use_compact_form;
+
 		pjsip_use_compact_form = PJ_TRUE;
 	}
 
@@ -103,6 +106,9 @@ static int system_apply(const struct ast_sorcery *system_sorcery, void *obj)
 	sip_threadpool_options.idle_timeout = system->threadpool.idle_timeout;
 	sip_threadpool_options.max_size = system->threadpool.max_size;
 
+	pjsip_cfg()->endpt.disable_tcp_switch =
+		system->disable_tcp_switch ? PJ_TRUE : PJ_FALSE;
+
 	return 0;
 }
 
@@ -141,6 +147,8 @@ int ast_sip_initialize_system(void)
 			OPT_UINT_T, 0, FLDSET(struct system_config, threadpool.idle_timeout));
 	ast_sorcery_object_field_register(system_sorcery, "system", "threadpool_max_size", "0",
 			OPT_UINT_T, 0, FLDSET(struct system_config, threadpool.max_size));
+	ast_sorcery_object_field_register(system_sorcery, "system", "disable_tcp_switch", "no",
+			OPT_BOOL_T, 1, FLDSET(struct system_config, disable_tcp_switch));
 
 	ast_sorcery_load(system_sorcery);