Mitel 5000, Twilio, and SIP Integration

[mkswanson]

We are currently using Twilio as an IVR.  We have assigned DID to each hunt group and are forwarding to those.  It works, but it is more expensive than SIP, and there isn't the same flexibility we'd like. 

Does anyone have any documentation or other guidance on how we can integrate Twilio/SIP with our Mitel 5000's?  I have an in-house Mitel resource that should be able to follow it.

PS...I'm also willing to hire someone to consult/do it if anyone out there is interested.

Thanks!

[Tech Electronics]

mkswanson,

What exactly are you doing with Twillo?

What else are you wanting?

What is your current solution not providing or what makes it ineffective?

Thanks,

TE


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[mkswanson]

We are using Twillio as an IVR for a call center. Our application retrieves user input via text and speech, completes database lookups, and creates a service call that is passed off to our helpdesk agents.

Twillio charges about double for a call to a SIP endpoint vs a PSTN endpoint, so there is quite a bit of financial incentive to use SIP vs carrier calls.

Because we’re forwarding to a hunt group, we can’t use our scripting logic for intelligent roting/skills based assignment/etc. We could potentially assign a DID to every potential extension, but that isn’t really practical. Until we either forward to individual extensions or DID for each agent, we can’t do any kind of screen pop, either.

mkswanson,

What exactly are you doing with Twillo?

What else are you wanting?

What is your current solution not providing or what makes it ineffective?

Thanks,

TE


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[Tech Electronics]

mkswanson,

So since you are a call center are you also using Mitel's MiContact Center Office which has Intelligent Router built-in to the product?

I am not sure what SIP vs PSTN has to do with Twilio other than what they charge to pass the calls along or am I missing something there.

So, you are saying that although you collected the information and gathered it via some sort of ODBC you have no way to get the call to the desired agent that could best help your customer without assigning a DID to each agent and then creating some sort of logic to determine where to send the call to that particular DID?

Thanks,

TE

[mkswanson]

We are not using MiContact Center Office. We are using several connected 5000’s with CSM. It’s a small call center, and it’s buikt on the older 5000 platform because of previous decisions -we’ve faced several integration challenges over the years, but it’s still a very solid platform with too much life left in it to consider a significant change, so we’re making due.

Really, the request has nothing to do with Twilio other than Twilio happens to be the SIP peer. At its simplest, we just want to establish SIP connectivity between “X” application/service and our Mitel 5000 environment.

We have the IVR (Twilio) application gathering the information, performing call logging/case creation (previously a manual process), and forwarding to one of several hunt groups which are currently based on the type of product being supported, the customer’s location and their entitlements. There’s opportunity to take it to the next level - but we need to overcome the SIP obstacle first so we can more easily send calls to specific extensions (which I wouldn’t think is that complicated, but maybe it is...or isn’t supported?).

[Tech Electronics]

mkswanson,

CSM is now call MiContact Center Office and it does have a version of Intelligent Router built-in to it as well at certain versions.

What version of software is your 5000 at? Is it a CS Controller or an HX Controller?

What SIP issues are you trying to overcome? Basically FXS is a simplified analog extension on this platform and FXO has all of the basic features, but works no different than analog or digital trunking.

Thanks,

TE

[mkswanson]

I’ll get the software versions posted tomorrow, but they're the HX controllers.

We haven’t gotten past step one - currently we have no SIP configuration, and we’re struggling to find documentation on how to get through the initial configuration. We were dealers quite a few years ago (we divested that business unit), so we self-support, but haven’t kept up with new features very well.

We do carry software maintenance, so we are entitled to any necessary software upgrades.

[Tech Electronics]

mkswanson,

Ah, I see now. Well if you can tell me what your software version is and what Twilio is providing you I can help you setup any SIP you need on the system.

Since you were a provider at one point I assume you know that you will need the correct type of licensing for your system depending on whether Twilio needs you to support FXO or FXS; my assumption is FXO. Also, the latest version of software 6.3 SP1 PR1 offers many bug fixes and better security than older versions of software when it comes to SIP, but it doesn't necessarily add too many more features or functionality than previous versions.

If you don't mind I would like to see a document at the end of all of this when we get your Twilio integration figured out to help others who may want to set that up. You won't need to get into any specifics on your code with Twilio, but how your connections are setup and what options if any work and don't work would be a great help for others in the future.

Thanks,

TE

[mkswanson]

Absolutely, and thanks for your help/engagement so far!  We can definitely document our experience. 

I'll visit with our Mitel guy in the morning and we'll get the specifics.

Thanks again!

[mkswanson]

Our HX controllers are running release version 6.0 SP2, Call processing version 6.0.11.95.

Below are the general SIP trunk configuration guides.
https://www.twilio.com/docs/sip-trunking/sample-configuration

And here's one for Mitel Business:
https://www.twilio.com/docs/documents/26/Twilio_Mitel_MiVoice_Sip.pdf

We're honestly not sure what exactly needs to be configured.  The goal today is to be able to receive calls from Twilio via SIP, so I don't think we need to implement the SIP trunk.  At some point, it would be nice to be able to make calls outgoing, too, which I would think would require it.

Thanks for your guidance, and sorry I'm not as well-versed as I'd like to be.

[Tech Electronics]

mkswanson,

Try this basic SIP Setup guide I created and see how far that gets us.

Thanks,

TE

[mkswanson]

Thanks...we'll give this a try and report back.

[aklein]

It looks like you will want to use a Twilio <Dial><Sip> to reach your Mitel over SIP.

The below links will help you there.

Use SIP With Twilio
https://www.twilio.com/docs/voice/api/sip-interface

TwiML Voice: <Sip>
https://www.twilio.com/docs/voice/twiml/sip

We just send a vanilla RFC 3261 SIP INVITE to your Mitel using SIP/UDP, SIP/TCP, or SIP/TLS.

You will want to use G.711U/PCMU as the Codec and RFC 2833 to handle DTMF.

Regards,
Alan

[michaelFF]

Tech Electronics,

I have been looking all over the internet for basic instructions for using a Mitel 250/5000 with Twilio Elastic SIP trunking, and this document essentially is the best resource that I found. Thank you.

I was able to get both inbound and outbound working, and when it works, it works great. But there is one issue that reoccurs and I'm not sure what is causing it. The system, the Twilio SIP trunk, our internet connection?

What happens is that after a period of a few weeks, usually 2-3, suddenly the outbound calling stops working. Inbound continues working perfectly fine. When trying to make an outbound call on the SIP trunk, the phone flashes and give the error "TG 92006 IS UNPLUGGED". TG 92006 is the trunk group setup with the Twilio sip trunk. I initially had no idea how to resolve the issue, I went as far as recreating the trunk group. Nothing worked. And then I simply restarted the PBX and it worked again for outbound. For another few weeks.

In the Mitel system, I saw that when the outbound on the SIP trunk is not working, the SIP Trunk is set to “Out-of-Service”. So I switched the SIP trunk into Maintenance Out-of-Service and then back to In-Service. I then dialed 92006 and got a dial-tone. I proceeded to dial a phone number, and it seemed to sit there (no dialing sound, no sound at all) as if it was waiting. After about twenty seconds  it gives the error “DESTINATION IS NOT RESPONDING”.

After a couple tries like this, it then begins to give the TG 92006 IS UNPLUGGED error again. This seems to be the point at which the SIP Trunk switches itself to “Out-of-Service”.

I can repeat the above and reproduce this sequence each time. Nothing seems to get the outbound dialing working except for restarting the system. And as to what is the cause ... I wish I knew.

I did this while looking at the SIP logs. The only thing I saw that seemed to coincide with the outbound dialing attempts when they are failing, is the following error:

-01:762- 21:08 07-09 M6127 WRN EG CP SIP - sip_interface_device_t::send_INVITE error during send


So I'm wondering if anyone else who has gotten Mitel 250/5000 to work with Twilio Elastic SIP trunking has experienced this, or might have any idea why this is happening. I'm also wondering (and toying with the idea), that if, in fact, the only resolution to this problem is a restart of the system, if I can set/program the system to reboot itself on a daily basis, say at 5am in the morning. Either in the system or just connect the PBX to something like a programmed power outlet that cuts power once daily for 15 seconds.

Because except for this one problem, it works completely and perfectly fine the rest of the time. We are on voice processor version 6.0.11.87 and db programming version 6.0.11.79

[Tech Electronics]

MichaelFF,

Sorry to hear you are having issues with this setup. It sounds to me like the system is having registration issues with Twilio at some point. You will need to check your SIP logs to see when this happens.

Your bandaid of rebooting the system may work if it ends up being a system resource issue causing the problem.

Thanks,

TE


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