diff --git a/src/api/api.go b/src/api/api.go
index a3db628..3ec81a2 100644
--- a/src/api/api.go
+++ b/src/api/api.go
@@ -324,8 +324,14 @@ func (a *Api) RegisterNumber(c *gin.Context) {
 
 	err = a.signalClient.RegisterNumber(number, req.UseVoice, req.Captcha)
 	if err != nil {
-		c.JSON(400, gin.H{"error": err.Error()})
-		return
+		switch err.(type) {
+		case *client.InvalidTransportError:
+			c.JSON(400, Error{Msg: "Couldn't use SMS verification to register the specified number. Wait 60 seconds and try again with {\"use_voice\": true}"})
+			return
+		default:
+			c.JSON(400, Error{Msg: err.Error()})
+			return
+		}
 	}
 	c.Writer.WriteHeader(201)
 }
diff --git a/src/client/client.go b/src/client/client.go
index 55671ee..5dc5985 100644
--- a/src/client/client.go
+++ b/src/client/client.go
@@ -749,6 +749,8 @@ func (s *SignalClient) About() About {
 }
 
 func (s *SignalClient) RegisterNumber(number string, useVoice bool, captcha string) error {
+	var err error
+	var jsonRpc2Client *JsonRpc2Client
 	if s.signalCliMode == JsonRpc {
 		type Request struct {
 			UseVoice bool   `json:"voice,omitempty"`
@@ -765,12 +767,11 @@ func (s *SignalClient) RegisterNumber(number string, useVoice bool, captcha stri
 			request.Captcha = captcha
 		}
 
-		jsonRpc2Client, err := s.getJsonRpc2Client()
+		jsonRpc2Client, err = s.getJsonRpc2Client()
 		if err != nil {
 			return err
 		}
 		_, err = jsonRpc2Client.getRaw("register", nil, request)
-		return err
 	} else {
 		command := []string{"--config", s.signalCliConfig, "-a", number, "register"}
 
@@ -782,9 +783,16 @@ func (s *SignalClient) RegisterNumber(number string, useVoice bool, captcha stri
 			command = append(command, []string{"--captcha", captcha}...)
 		}
 
-		_, err := s.cliClient.Execute(true, command, "")
-		return err
+		_, err = s.cliClient.Execute(true, command, "")
 	}
+
+	if err != nil {
+		if !useVoice && strings.Contains(err.Error(), "StatusCode: 400 (InvalidTransportModeException)") {
+			return &InvalidTransportError{Description: "Couldn't use SMS verification to register number."}
+		}
+	}
+
+	return err
 }
 
 func (s *SignalClient) UnregisterNumber(number string, deleteAccount bool, deleteLocalData bool) error {
diff --git a/src/client/errors.go b/src/client/errors.go
index 5344334..14237ed 100644
--- a/src/client/errors.go
+++ b/src/client/errors.go
@@ -23,3 +23,11 @@ type InternalError struct {
 func (e *InternalError) Error() string {
 	return e.Description
 }
+
+type InvalidTransportError struct {
+	Description string
+}
+
+func (e *InvalidTransportError) Error() string {
+	return e.Description
+}