diff --git a/reach/client/protocol/modem.go b/reach/client/protocol/modem.go
index a58ca5d..93cb60a 100644
--- a/reach/client/protocol/modem.go
+++ b/reach/client/protocol/modem.go
@@ -5,6 +5,7 @@ type SetModemOptions struct {
 	Type     *string
 	Username *string
 	Password *string
+	Pin      *string
 }
 
 type SetModemOptionsFunc func(opts *SetModemOptions)
@@ -34,8 +35,15 @@ func WithUsername(value string) SetModemOptionsFunc {
 		opts.Username = &value
 	}
 }
+
 func WithPassword(value string) SetModemOptionsFunc {
 	return func(opts *SetModemOptions) {
 		opts.Password = &value
 	}
 }
+
+func WithPin(value string) SetModemOptionsFunc {
+	return func(opts *SetModemOptions) {
+		opts.Pin = &value
+	}
+}
diff --git a/reach/client/protocol/v2/model/modem.go b/reach/client/protocol/v2/model/modem.go
index 805e727..f529fd2 100644
--- a/reach/client/protocol/v2/model/modem.go
+++ b/reach/client/protocol/v2/model/modem.go
@@ -3,12 +3,13 @@ package model
 // type : null, pap_chap, pap, chap
 // if type selected, username and password are mandatory
 type ModemAuthentication struct {
-	Authentication struct {
-		Apn      string `json:"apn"`
+	Authentication *struct {
+		Apn      string `json:"apn,omitempty"`
 		Type     string `json:"type,omitempty"`
 		Username string `json:"username,omitempty"`
 		Password string `json:"password,omitempty"`
-	} `json:"authentication"`
+	} `json:"authentication,omitempty"`
+	Pin string `json:"pin,omitempty"`
 }
 
 type ModemConfiguration struct {
diff --git a/reach/client/protocol/v2/operations.go b/reach/client/protocol/v2/operations.go
index 3522bba..7c5f259 100644
--- a/reach/client/protocol/v2/operations.go
+++ b/reach/client/protocol/v2/operations.go
@@ -366,20 +366,29 @@ func (o *Operations) SetBaseCorrections(ctx context.Context, funcs ...protocol.S
 func (o *Operations) SetModem(ctx context.Context, funcs ...protocol.SetModemOptionsFunc) error {
 	opts := protocol.NewSetModemOptions(funcs...)
 	modem := &model.ModemAuthentication{}
-	if opts.Apn != nil {
-		modem.Authentication.Apn = *opts.Apn
+	if opts.Pin != nil {
+		modem.Pin = *opts.Pin
 	}
 
-	if opts.Type != nil {
-		modem.Authentication.Type = *opts.Type
-	}
-
-	if opts.Password != nil {
-		modem.Authentication.Password = *opts.Password
-	}
-
-	if opts.Username != nil {
-		modem.Authentication.Username = *opts.Username
+	if opts.Apn != nil || opts.Type != nil || opts.Username != nil || opts.Password != nil {
+		modem.Authentication = &struct {
+			Apn      string `json:"apn,omitempty"`
+			Type     string `json:"type,omitempty"`
+			Username string `json:"username,omitempty"`
+			Password string `json:"password,omitempty"`
+		}{}
+		if opts.Apn != nil {
+			modem.Authentication.Apn = *opts.Apn
+		}
+		if opts.Type != nil {
+			modem.Authentication.Type = *opts.Type
+		}
+		if opts.Username != nil {
+			modem.Authentication.Username = *opts.Username
+		}
+		if opts.Password != nil {
+			modem.Authentication.Password = *opts.Password
+		}
 	}
 
 	if _, err := o.PostModem(ctx, modem); err != nil {