I’m currently working on a project using Twilio and Yealink T31 hardphones. I’m leveraging Twilio’s <Client> and <SIP> verbs for handling calls, and using <Enqueue> and <Queue> to park calls. In my Yealink Dashboard I have selected transfer mode for call parking, so it hits my referUrl that I specify while doing the sip call.

The issue I’m facing is that the BLF (Busy Lamp Field) on my Yealink T31 phones doesn’t light up when a call is parked. Ideally, the phone that parks the call should show a red BLF indicator, and other phones on the network should show a blinking green BLF indicator.

And my Yealink DSS Key configuration is as follows:

Park Key: *10001 (Park Code)
Retrieve Key: *20001 (Retrieve Code)

Despite this setup, the BLF indicators don’t change when a call is parked. I know that there must be some more configuration required to make it work but I am not able to figure out what am I missing in the configuration?

I did some research on the internet and got to know about PBX systems. But all of them seem unfit for my usecase. The product I am building will have multiple companies onboarded and each of them will have their own set of SIP and Client’s. Currently I have a Twilio SIP domain and I register accounts for company’s number and use it directly in the Yealink devices.

Here’s some reference code that I am using:

For Retreive Call Park –

const response = new twilio.twiml.VoiceResponse()
const dial = response.dial();
                    dial.queue(`${company.data.company_id}_${toFormatted?.toString()?.substring(4)}`); // basically companyid_lotNumber
return response.toString();

Similar as above for Call Park, but dial.enqueue instead of dial.queue.

For calling to SIP phones –

dial = voice_response.dial({
  callerId: from,
  action: `${process.env.ENV_URL}/voice/sip-url`,
  method: 'POST',
  referUrl: `${process.env.ENV_URL}/voice/transfer-sip`,
});

dial.sip({
  statusCallbackEvent: 'answered completed',
  statusCallback: `${process.env.ENV_URL}/voice/save-logs-callback`,
  statusCallbackMethod: 'POST',
}, sip);