Sending SMS from ASP.NET Web Application Using Twilio API

RichardS...

SOLVED CLOSED ACTIVE ANSWERED
User: RichardSa
Posted: on Nov 14, 2025 11:44 PM
Forum: ASP.Net Web Forms
Answer: 1
Views: 1385

I am attempting to implement a feature that allows a user to send an SMS to a mobile number from a web application using the Twilio API. The application setup consists of two text boxes: DestnationPhone.Text SmsMessage.Text In this feature, a user will enter the mobile phone number in the DestnationPhone text box and the message in the SmsMessage text box. After this, the user will click the send button to send the message to the recipient's mobile number. I would like guidance on how to achieve this using the Twilio API. Below is the code I have attempted, but I am encountering errors on two lines, and I am unsure if it is correct. Please see the code snippet in the image below for reference: Can someone provide assistance on how to properly implement this feature?

After weesk of trying , this is the new error I got:

Credetials have not been initialized or changed, please call TwilioClient.init()

This is my HTML and Code

HTML
<form id="form1" runat="server">
        <div>
            <div class="row">
                <div class="col-md-12">
                    <div class="form-group">
                        <div class="input-group">
                            <asp:TextBox ID="DestinationNumber" placeholder="Mobile Number" Width="300px" Height="30px" CssClass="form-control" Font-Size="10pt" runat="server"></asp:TextBox>
                        </div>
                    </div>
                </div>
            </div>
            <div class="row">
                <div class="col-md-12">
                    <div class="form-group">
                        <div class="input-group">
                            <asp:TextBox ID="SMSmessage" runat="server" AutoCompleteType="None" CssClass="form-control" placeholder="Your message" TextMode="MultiLine" Style="overflow: hidden; font-size: 10pt; resize: none;" oninput="Resize(this)" />
                            <script type="text/javascript">
                                function Resize(textbox) {
                                    textbox.style.height = "";
                                    textbox.style.height = Math.min(textbox.scrollHeight, 300) + "px";
                                }
                            </script>
                        </div>
                    </div>
                </div>
            </div>
            <asp:Button ID="Button8" runat="server" Text="Button" CssClass="btn btn-primary" OnClick="Button8_Click" />
        </div>
    </form>

{
            // Get the Twilio credentials
            string accountSid = "ACf3e50202f5988c915d37e995a62b51ec"; // Replace with your Account SID
            string authToken = "166eb90fe50b38b7ba1bb4d841852ec8"; // Replace with your Auth Token

            // Get the phone number and message text from the TextBox
            string phoneNumber = DestinationNumber.Text;
            string messageBody = SMSmessage.Text;

            // Initialize the Twilio client
            TwilioRestClient client = new TwilioRestClient(accountSid, authToken);

            // Create a new SMS message
            try
            {
                ITwilioRestClient twilioRestClient = null;
                var message = MessageResource.Create(
                to: new PhoneNumber("+15017122661"),
                from: new PhoneNumber("+15017122661"),
                body: "Hey there!",
                // Here's where you inject the custom client
                
                client: twilioRestClient
);
           }
            catch (Exception ex)
            {
                Response.Write("<script>alert('" + ex.Message + "');</script>");
            }
        }

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Mudassar

0 1

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User: Mudassar
Replied: on Nov 14, 2025 11:45 PM
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Hi,

For twillio you need to contact their support as it is not possible for me to debug or check as it will require registration for the same.

Thanks

Mudassar

0 2

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User: Mudassar
Replied: on Nov 20, 2025 08:21 AM
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For twillio you need to contact support as we don't have its API, thus cannot test your code

RichardS...

0 3

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User: RichardSa
Replied: on Dec 03, 2025 11:58 PM
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I finally found a solution

CODE:

protected void ButtonSms_Click(object sender, EventArgs e)
        {
            SendSms();
        }

public void SendSms() { try { // Twilio credentials string accountSid = "ACf3e50202f5988c915d37e995a62b51ec"; // Replace with your Account SID string authToken = "166eb90fe50b38b7ba1bb4d841852ec8"; // Replace with your Auth Token

// Get the phone number and message text from the TextBox controls string toPhoneNumber = DestinationNumber.Text; string messageBody = SMSmessage.Text;

// Your Twilio phone number (must be SMS-enabled) string fromPhoneNumber = "+13232489076"; // Replace with your Twilio number

// Initialize the Twilio client TwilioClient.Init(accountSid, authToken);

// Send the SMS var message = MessageResource.Create( to: new PhoneNumber(toPhoneNumber), from: new PhoneNumber(fromPhoneNumber), body: messageBody );

// Optionally, show a success message Response.Write("<script>alert('Message sent! SID: " + message.Sid + "');</script>"); } catch (Exception ex) { Response.Write("<script>alert('Error: " + ex.Message + "');</script>"); } }

RichardS...

0 4

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ANSWER
User: RichardSa
Replied: on Dec 04, 2025 12:00 AM
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I found a solution to this my problem

    protected void ButtonSms_Click(object sender, EventArgs e)
        {
            SendSms();
        }
        public void SendSms()
        {
            try
            {
                // Twilio credentials
                string accountSid = "ACf3e50202f5988c915d37e995a62b51ec"; // Replace with your Account SID
                string authToken = "166eb90fe50b38b7ba1bb4d841852ec8"; // Replace with your Auth Token

                // Get the phone number and message text from the TextBox controls
                string toPhoneNumber = DestinationNumber.Text;
                string messageBody = SMSmessage.Text;

                // Your Twilio phone number (must be SMS-enabled)
                string fromPhoneNumber = "+13232489076"; // Replace with your Twilio number

                // Initialize the Twilio client
                TwilioClient.Init(accountSid, authToken);

                // Send the SMS
                var message = MessageResource.Create(
                    to: new PhoneNumber(toPhoneNumber),
                    from: new PhoneNumber(fromPhoneNumber),
                    body: messageBody
                );

                // Optionally, show a success message
                Response.Write("<script>alert('Message sent! SID: " + message.Sid + "');</script>");
            }
            catch (Exception ex)
            {
                Response.Write("<script>alert('Error: " + ex.Message + "');</script>");
            }
        }

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Sending SMS from ASP.NET Web Application Using Twilio API

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