sip-outbound.cs

using System.Net;
using System.Text.RegularExpressions;
using Twilio.TwiML;

public static async Task<HttpResponseMessage> Run(HttpRequestMessage req, TraceWriter log)
{
    log.Info($"C# HTTP trigger function processed a request. RequestUri={req.RequestUri}");

    var data = await req.Content.ReadAsStringAsync();

    data = data.Replace("%3A", ":");
    data = data.Replace("%40", "@");

    log.Info(data);

    Dictionary<string,string> formValues = data.Split('&')
        .Select(value => value.Split('='))
        .ToDictionary(pair => pair[0], pair => pair[1]);
    
    var to = formValues["To"];

    Regex exp_e164_pstn = new Regex(@"^sip:([+][0-9]{10,14})@");
    Match match_e164_pstn = exp_e164_pstn.Match(to);

    Regex exp_011_pstn = new Regex(@"^sip:011([0-9]{10,14})@");
    Match match_011_pstn = exp_011_pstn.Match(to);

    Regex exp_us_pstn = new Regex(@"^sip:[+]?1?([0-9]{10})@");
    Match match_us_pstn = exp_us_pstn.Match(to);
    
    if (match_e164_pstn.Success) {
        to = String.Format("{0}", match_e164_pstn.Groups[1]);
    } else if (match_011_pstn.Success) {
        to = String.Format("+{0}", match_011_pstn.Groups[1]);
    } else if (match_us_pstn.Success) {
        to = String.Format("+1{0}", match_us_pstn.Groups[1]);
    }

    log.Info(to);

    var response = new TwilioResponse();

    if (to.StartsWith("sip:")) {
        response.Dial(new Sip(to));
    } else {
        string caller_id = System.Environment.GetEnvironmentVariable("TWILIO_CALLERID", EnvironmentVariableTarget.Process);
        response.Dial(to, new { callerId=caller_id });
    }

    return new HttpResponseMessage
    {
        Content = new StringContent(response.ToString(), System.Text.Encoding.UTF8, "application/xml")
    };
}