I am trying to forward calls to my sip device from my twilio number. However this is currently not working as expected because Twilio does not like SIP providers using a load balanced url. In my case the sip uri ends with @in.callcentric.com which in turn sends requests to three servers. If I directly use one of the servers, i.e. @alpha11.callcentric.com:5070 instead of @in.callcentric.com it works. However this is not ideal imo.
I have found a node module that does SRV lookups. Is this something I could use with twilio functions to solve the problem?
Is there a way to force twilio to lookup the SRV record and automatically use that to forward the calls?
Using NPM's inbuilt dns module I was able to get things working. This is how my function looks now. Seems to be working okay.
const dns = require('dns');
let sipUri = '1777xxxxxxxxxx@in.callcentric.com';
let protocol = 'udp';
let region = 'us2' ;
exports.handler = function(context, event, callback) {
var user = sipUri.split('@')[0];
var host = sipUri.split('@')[1];
// generate the TwiML to tell Twilio how to forward this call
let twiml = new Twilio.twiml.VoiceResponse();
const dial = twiml.dial();
dns.resolveSrv('_sip._'+protocol+'.'+host, (err, addresses) => {
var resolvedhost = addresses[0].name+':'+addresses[0].port;
dial.sip('sip:'+user+'@'+resolvedhost+';region='+region);
console.log(twiml.toString());
// return the TwiML
callback(null, twiml);
});
};
This manually queries the hostname for SRV records and then uses the first result returned. Does not take weight and priorities into account.