/sipgateio-callevents-python

A demonstration of how to receive and process webhooks from sipgate.io

Primary LanguagePythonThe UnlicenseUnlicense

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sipgate.io Python call events example

This example demonstrates how to receive and process webhooks from sipgate.io.

For further information regarding the push functionalities of sipgate.io please visit https://developer.sipgate.io/push-api/api-reference/

Prerequisites

  • python3
  • pip3

Enabling sipgate.io for your sipgate account

In order to use sipgate.io, you need to book the corresponding package in your sipgate account. The most basic package is the free sipgate.io S package.

If you use sipgate basic or simquadrat you can book packages in your product's feature store. If you are a sipgate team user logged in with an admin account you can find the option under Account Administration > Plans & Packages.

How sipgate.io webhooks work

What is a webhook?

A webhook is a POST request that sipgate.io makes to a predefined URL when a certain event occurs. These requests contain information about the event that occurred in application/x-www-form-urlencoded format.

This is an example payload converted from application/x-www-form-urlencoded to JSON:

{
  "event": "newCall",
  "direction": "in",
  "from": "492111234567",
  "to": "4915791234567",
  "callId":"12345678",
  "origCallId":"12345678",
  "user": [ "Alice" ],
  "xcid": "123abc456def789",
  "diversion": "1a2b3d4e5f"
}

sipgate.io webhook events

sipgate.io offers webhooks for the following events:

  • newCall: is triggered when a new incoming or outgoing call occurs
  • onAnswer: is triggered when a call is answered – either by a person or an automatic voicemail
  • onHangup: is triggered when a call is hung up
  • dtmf: is triggered when a user makes an entry of digits during a call

Note: Per default, sipgate.io only sends webhooks for newCall events. To subscribe to other event types you can reply to the newCall event with an XML response. This response includes the event types you would like to receive webhooks for as well as the respective URL they should be directed to. You can find more information about the XML response here: https://developer.sipgate.io/push-api/api-reference/#the-xml-response

Configure webhooks for sipgate.io

You can configure webhooks for sipgate.io as follows:

  1. Navigate to console.sipgate.com and login with your sipgate account credentials.
  2. Select the Webhooks > URLs tab in the left side menu
  3. Click the gear icon of the Incoming or Outgoing entry
  4. Fill in your webhook URL and click save.
    Note: your webhook URL has to be accessible from the internet. (See the section Making your computer accessible from the internet)
    Example: Assuming your server's address was example.localhost.run, the address you'd need to set in the webhook console would be https://example.localhost.run/new-call.
  5. In the sources section you can select what phonelines and groups should trigger webhooks.

A word on security

Although sipgate.io can work with both HTTP and HTTPS connections, it is strongly discouraged to use plain HTTP as the webhooks contain sensitive information. The service localhost.run also supports HTTPS, so for development you will be fine using that. For production, it is important to note that sipgate.io does not accept self-signed SSL certificates. If you need a certificate for your server, you can easily get one at Let´s Encrypt.

Making your computer accessible from the internet

There are many possibilities to obtain an externally accessible address for your computer. In this example we use the service localhost.run which sets up a reverse ssh tunnel that forwards traffic from a public URL to your localhost. The following command creates a subdomain at localhost.run and sets up a tunnel between the public port 80 on their server and your localhost:8080:

$ ssh -R 80:localhost:8080 ssh.localhost.run

If you run this example on a server which can already be reached from the internet, you do not need the forwarding. In that case, the webhook URL needs to be adjusted accordingly.

Get the code example:

Clone Repository with HTTPS

git clone https://github.com/sipgate-io/sipgateio-callevents-python.git

Clone Repository with SSH

git clone git@github.com/sipgate-io/sipgateio-callevents-python.git

Navigate to the project's root directory.

Install dependencies:

Please run the following command:

$ pip3 install -r requirements.txt

Configuration

Create the .env by copying the .env.example and set the values according to the comment above the variables.

The WEBHOOK_URL is the URL under which your server is accessible from the internet (i.e. the URL you set up in the webhooks console minus the "/new-call" portion) (See Configure webhooks for sipgate.io).

In the server.py the ON_ANSWER_URL and ON_HANGUP_URL is set to the WEBHOOK_URL followed by a suffix depending on the event type.

ON_ANSWER_URL = WEBHOOK_URL + "/on-answer"
ON_HANGUP_URL = WEBHOOK_URL + "/on-hangup"

Execution

Run the application:

python -m call_events

How It Works

In the __main__.py, which is a starting point of the application, we import the server module from our file server.py on the same directory. The library logging is imported to reduce the log report of the Flask framework to only print errors. The server module contains a Flask application called app, which is started by calling its run() method with the desired port.

import call_events.server as server
import logging
from dotenv import load_dotenv
import os

load_dotenv()

if __name__ == "__main__":
    log = logging.getLogger('werkzeug')
    log.setLevel(logging.ERROR)

    server.app.run(port=int(os.environ.get("WEBHOOK_PORT")))

The application's behavior is defined in the server.py script.

First, the necessary libraries are imported, Flask for starting the server and ElementTree for creating the xml responses:

import flask
import xml.etree.ElementTree as ET

Following the HTTP server gets created using the Flask framework:

app = flask.Flask(__name__)

Afterwards, the routes are specified which handles the incoming POST requests.

With the function handle_new_call() a xml response is returned containing urls for the following events.

@app.route("/new-call", methods=["POST"])
def handle_new_call():
    request = flask.request
    request_data = request.form.to_dict()

    caller = request_data.get("from", "[unknown]")
    callee_number = request_data.get("to", "[unknown]")

    print("New call from {} to {} is ringing...".format(caller, callee_number))

    xml_response = build_xml_response()
    return xml_response, 200, {"Content-Type": "application/xml"}

Within the function handle_new_call(), the caller and callee_number are read from the request data and are printed.

caller = request_data.get("from", "[unknown]")
callee_number = request_data.get("to", "[unknown]")

print("New call from {} to {} is ringing...".format(caller, callee_number))

Afterwards the xml response get created. Therefore the function build_xml_response() is called. It returns a xml response string and the corresponding HTTP status code 204 indicating that there is no content:

xml_response = build_xml_response()

After that the attributes onAnswer and onHangup are added to the Response element containing the url earlier defined for the following events. Within the build_xml_response() function, an instance of an ElementTree is created. The created element is called Response.

def build_xml_response():
    response = ET.Element("Response")
    response.set("onAnswer", ON_ANSWER_URL)
    response.set("onHangup", ON_HANGUP_URL)
    xml_response = ET.tostring(response)
    return xml_response

The function handle_on_answer() is similar to the previous one handle_new_call(), except there is no xml response.

@app.route("/on-answer", methods=["POST"])
def handle_on_answer():
    request = flask.request
    request_data = request.form.to_dict()

    caller = request_data.get("from", "[unknown]")
    callee_name = request_data.get("user", "[unknown]")

    print("{} answered call from {}".format(callee_name, caller))

    return "This response will be discarded", 200

For the Hangup event a method handle_on_hangup() is created, to notify that the call has been hung up.

@app.route("/on-hangup", methods=["POST"])
def handle_on_hangup():
    print("The call has been hung up")

    return "This response will be discarded", 200

Common Issues

web app displays "Feature sipgate.io not booked."

Possible reasons are:

  • the sipgate.io feature is not booked for your account

See the section Enabling sipgate.io for your sipgate account for instruction on how to book sipgate.io

"OSError: [Errno 98] Address already in use"

Possible reasons are:

  • another instance of the application is already running
  • the specified port is in use by another application

"PermissionError: [Errno 13] Permission denied"

Possible reasons are:

  • you do not have permission to bind to the specified port. This usually occurs if you try to use port 80, 443 or another well-known port which can only be bound with superuser privileges

Call happened but no webhook was received

Possible reasons are:

  • the configured webhook URL is incorrect
  • the SSH tunnel connection was closed in the background
  • webhooks are not enabled for the phoneline that received the call

Related

Contact Us

Please let us know how we can improve this example. If you have a specific feature request or found a bug, please use Issues or fork this repository and send a pull request with your improvements.

License

This project is licensed under The Unlicense (see LICENSE file).

External Libraries

This code uses the following external libraries

sipgate.io | @sipgateio | API-doc