Pass Custom SIP Headers

    Overview

    SIP headers (also called SIP fields) are part of every HTTP request made by an outbound call. They can convey message attributes to ensure that information packets travel along the correct path between devices on different networks.

    SIP headers are categorized into four main types: record-route headers, route headers, via headers, and contact headers. They always have the format

    <header_name>:<value>
    

    Plivo SIP headers are always prefixed with X-PH-. Only characters [A-Z], [a-z], and [0-9] are allowed as part of either a SIP header name or value to ensure that you can encode them in a URL. You can use multiple header fields by entering them as a comma-separated list:

    head1=val1,head2=val2,head3=val3,...,headn=valn
    

    You can use custom SIP headers to pass information (such as customer ID or product information) from a front-end application to a back-end application and vice versa.

    If you’re using a SIP endpoint and you’ve configured it to send custom SIP headers, Plivo will send the SIP headers with your HTTP request.

    You can pass custom SIP headers either by using our PHLO visual workflow builder or our APIs and XML documents. Follow the instructions in one of the tabs below.

    To make an outbound call with custom SIP headers, you can create and deploy a PHLO with a few clicks on the PHLO canvas. PHLO also lets you visually construct your entire use-case. With PHLO, you only pay for calls you make/receive, and building with PHLO is free.

    Outline

    Outbound- Call Flow

    Implementation

    In this section, we will guide you to create a PHLO to make an outbound call with custom SIP headers.

    Prerequisites

    1. Create a Plivo Account(if you don’t have one already): You can sign up with your work email address and complete the phone verification step using your mobile number.
    2. Set up your Dotnet dev environment: To set up your dev environment in your .NET(C#) programming language, please refer to the instructions available in the Set up Your Dotnet Dev Environment section.
    3. Buy a Plivo number(optional): You must have a voice-enabled Plivo phone number if you are willing to receive incoming calls. You can purchase numbers from the Numbers section of your Plivo Console. It is also possible to purchase numbers using the Numbers API.

    Create the PHLO

    You can create a PHLO by referring to the below instructions to make an outbound call with custom SIP headers:

    Create a PHLO for Outbound Calls with Custom SIP Headers

    • On the side navigation bar, click PHLO. The PHLO page will appear and display your existing PHLOs, if any. If this is your first PHLO, then the PHLO page will be empty.
    • Click Create New PHLO to build a new PHLO.
    • On the Choose your use-case window, click Build my own. The PHLO canvas will appear with the Start node.
      Note: The Start node is the starting point of any PHLO. You can choose between the four available trigger states of the Start node; Incoming SMS, Incoming Call, and API Request. For this PHLO, we will use the API Request trigger state.
    • From the list of components, on the left hand side, drag and drop the Initiate Call component onto the canvas. This will add a Initial Call node onto the canvas.
    • Connect the Start node with the Initiate Call node, using the API Request trigger state.
    • Configure the Initiate Call node with the caller ID using the From field. Enter the destination number you wish to call in the To field. Enter the custom SIP headers you wish to add in the Custom Headers field.
    • Once you have configured the node, click Validate to save the configurations.
    • Similarly, create a node for the Play Audio component and connect it to the Initiate Call node using the Answered trigger state.
    • Next, configure the Play Audio node to play a specific message to the user. For example, in this case, “Hello! you just received your first inbound call”.
    • Connect the Initiate Call node with the Play Audio node, using the Answered trigger state.
    • After you complete the configurations, provide a friendly name for your PHLO and click Save. Your PHLO is now ready. You can trigger the PHLO and test it out. For more information, refer to the following section.

    Set up Your Dotnet Dev Environment

    You must set up and install Dotnet Framework(.NET Framework 4.6 or higher) and Plivo’s Dotnet SDK to make an outbound call with custom SIP headers. Here’s how.

    Install Dotnet Framework

    Operating SystemInstructions
    macOS & LinuxYou would already have Dotnet Framework installed, you can check this by running the command dotnet --version in the terminal. If you do not have it installed, you can install it from here.
    WindowsTo install Dotnet Framework on Windows you can follow the instructions from here.

    Install Plivo .NET Nuget Package using Visual Studio

    • Create a new project in Visual Studio

      Create New Project

    • Choose a Template for the new project

      Choose Template

    • Install the Plivo Nuget package

      Manage Nuget packages Select Plivo Nuget package

    Trigger the PHLO

    Once you have created and setup your Dotnet dev envrironment, you can go to your Plivo Consolse and copy the PHLO_ID. You can integrate a PHLO into your application workflow by making an API request to trigger the PHLO with the required payload.

    With Static Payload

    You can choose to either configure the mandatory params required for a PHLO while creating the PHLO itself or, you can pass the params as payload while triggering the PHLO from your app.

    Note: When you configure the params while creating the PHLO, the values are hardcoded, and they act as static payload.

    With Static Payload

    Code

    Now, open the file in the CS project called Program.cs and paste the below code.

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    using System;
    using Plivo;
    
    namespace test_PHLO
    {
        class Program
        {
            public static void Main(string[] args)
            {
                var phloClient = new PhloApi("auth_id", "auth_token"); 
                var phloID = "phlo_id"; // replace the placeholder phlo_id with your PHLO_ID from Plivo Console
                var phlo = phloClient.Phlo.Get(phloID);   
                Console.WriteLine(phlo.Run());
            }
        }
    }
    

    With Dynamic Payload

    To use dynamic values for the parameters, you can use the liquid templating params while creating the PHLO and pass the values while triggering the PHLO.

    With Dynamic Payload

    Code

    Now, open the file in the CS project called Program.cs and paste the below code.

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    using System;
    using System.Collections.Generic;
    using Plivo;
    
    namespace test_PHLO
    {
        class Program
        {
            public static void Main(string[] args)
            {
                var phloClient = new PhloApi("auth_id", "auth_token");
                var phloID = "phlo_id"; // replace the placeholder phlo_id with your PHLO_ID from Plivo Console
                var phlo = phloClient.Phlo.Get(phloID); 
                var data = new Dictionary<string, object>
                {
                    { "from", "+14157778888" },
                    { "to", "+14157778889" }
    
                };  
                Console.WriteLine(phlo.Run(data));
            }
        }
    }
    

    You can get your Auth_ID and Auth_token from your dashboard AUTHID

    You can find the PHLO_ID on the PHLO Listing page. PHLO Listing

    Test and Validate

    You can save the file and run it.

    Note: If you are using a Plivo Trial account for this example, you can only make calls to phone numbers that have been verified with Plivo. Phone numbers can be verified at the Sandbox Numbers page.

    To make an outbound call with custom SIP headers in the traditional API/XML way, you can refer to the instructions in the below section to begin your implementation.

    Outline

    Custom SIP Headers- Call Flow

    Implementation

    In this section, we will show you how to add custom SIP headers. The following API enables you to make an outbound call(single destination) or a bulk outbound call to PSTN(s) or SIP endpoint(s).

    POST https://api.plivo.com/v1/Account/{auth_id}/Call/

    Prerequisites

    This section will guide you through how to use Plivo APIs to make voice calls from your application. First, let’s make sure you meet these prerequisites before we dive into the code.

    • Plivo Auth Id and Auth Token: You will find your Plivo Auth Id and Auth Token on the home screen of your Plivo Console. Click here to sign-up for a Plivo account if you haven’t already!

      Find Your Auth Credentials on Plivo Console

    • Plivo Phone Number(Optional): You can purchase numbers from the Numbers section of your Plivo Console and use the same as the caller ID for the outbound call. This number will also help you receive incoming calls as you must have a voice-enabled Plivo phone number to do the same. Please note that you can also purchase numbers using the Numbers API.

      Buy a New Plivo Number

    • Answer Url: When a call is answered by the destination_number, you can control the call flow with the help of the answer_url set in the API request. Plivo will invoke the answer_url specified as soon as the call is answered and expect a valid XML response with instructions to handle the call. For example, you can use https://s3.amazonaws.com/static.plivo.com/answer.xml as answer_url to test your first outgoing call. The XML response of this is:

      <Response> 
      <Speak>Congratulations! You've made your first outbound call!</Speak> 
      </Response>
      

      As you can tell, the XML above holds instructions to say ‘Congratulations! You’ve made your first outbound call!’ to the callee. You can find the entire list of Plivo XML verbs and their details in the XML Reference section of the website here.

    Set up Your Dotnet Dev Environment

    You must set up and install Dotnet Framework(.NET Framework 4.6 or higher) and Plivo’s Dotnet SDK to make an outbound call with Custom SIP headers. Here’s how.

    Install Dotnet Framework

    Operating SystemInstructions
    macOS & LinuxYou would already have Dotnet Framework installed, you can check this by running the command dotnet --version in the terminal. If you do not have it installed, you can install it from here.
    WindowsTo install Dotnet Framework on Windows you can follow the instructions from here.

    Install Plivo .NET Nuget Package using Visual Studio

    • Create a new project in Visual Studio

      Create New Project

    • Choose a Template for the new project

      Choose Template

    • Install the Plivo Nuget package

      Manage Nuget packages Select Plivo Nuget package

    Create the Outbound Call App with Custom SIP Headers

    Once you have the above prerequisites set, You can follow the below instructions to create an app to make an outbound call with custom SIP headers and leave a text-to-speech message once the call recipient answers the call.

    Now, open the file in the CS project called Program.cs and paste the below code.

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    /**
     * Example for Call Create
     */
    using System;
    using System.Collections.Generic;
    using Plivo;
    using Plivo.Exception;
    
    namespace PlivoExamples
    {
        internal class Program
        {
            public static void Main(string[] args)
            {
                var api = new PlivoApi("<auth_id>","<auth_token>");
                try
                {
                    var response = api.Call.Create(
                        to:new List<String>{"+14157654321"},
                        from:"+14151234567",
                        answerMethod:"GET",
                        answerUrl:"http://s3.amazonaws.com/static.plivo.com/answer.xml",
                        sipHeaders: "customer=johndoe"
                    );
                    Console.WriteLine(response);
                }
                catch (PlivoRestException e)
                {
                    Console.WriteLine("Exception: " + e.Message);
                }
            }
        }
    }
    
    Note:
    • Replace the placeholders auth_id & auth_token with your credentials from Plivo Console.
    • We recommend that you store your credentials in the auth_id & auth_token environment variables, so as to avoid the possibility of accidentally committing them to source control. If you do this, you can initialize the client with no arguments and it will automatically fetch them from the environment variables
    • You can use Environment.SetEnvironmentVariable Method to store environment variables and fetch them using Environment.GetEnvironmentVariable Method while initializing the client.
    • Replace the placeholder +14151234567 with the Phone number which you have purchased and +14157654321 with the phone number you will be making calls to.
    • Both plivo_source_number and +14157654321 should be in E.164 format

    Test and Validate

    Once you have created the Outbound Call App with custom SIP headers, Save the file and run it.

    Make outbound call

    Note: If you are using a Plivo Trial account for this example, you can only make calls to phone numbers that have been verified with Plivo. Phone numbers can be verified at the Sandbox Numbers page.

    Sample Response

    (201, {
            u'message': u'call fired',
            u'request_uuid': u'85b1d45d-bc12-47f5-89c7-ae4a2c5d5713',
            u'api_id': u'ad0e27a8-9008-11e4-b932-22000ac50fac'
        }
    )
    

    The SIP header can be seen as a query parameter in the answer_url

    /answer.xml?Direction=outbound&From=1111111111&ALegUUID=5260e820-958c-11e4-b6bf-498d468c930b&BillRate=0.00300&
    To=sip%3Aabcd150105094929%40phone.plivo.com&<mark>X-PH-Test=Sample</mark>&CallUUID=5260e820-958c-11e4-b6bf-498d468c930b&ALegRequestUUID=2202d0ab-a890-4199-8582-e7a2615cb23b&
    RequestUUID=2202d0ab-a890-4199-8582-e7a2615cb23b&SIP-H-To=%3Csip%3Aabcd150105094929%40phone.plivo.com%3E%3Btag%3D6U9J4.uVHI7KyEKSgD8vrPnAKQoR2QXc&
    CallStatus=in-progress&Event=StartApp