VOIP lines w/ Tele Interface

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duckfan98
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VOIP lines w/ Tele Interface

Post by duckfan98 » Fri Feb 06, 2015 2:15 pm

Greetings,

We just switched over our entire studio / station to VOIP service. However, now I am finding that VOIP doesnt like to play well with telco interfaces.... doh!.

Does anyone have a good recommendation on getting callers on the air, and still allowing mix minus / etc...without having to drop thousands on a Telos system?

Thanks!

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kkiddkkidd
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Re: VOIP lines w/ Tele Interface

Post by kkiddkkidd » Fri Feb 06, 2015 5:06 pm

I have several clients running a variety of digital and analog hybrids on various VOIP services and haven't had any complaints thus far. Digital codecs (BlueBox, etc) do not function reliably on VOIP but the on-air hybrids don't seem to notice the difference.

What are they doing?

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duckfan98
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Re: VOIP lines w/ Tele Interface

Post by duckfan98 » Fri Feb 06, 2015 5:08 pm

What are they doing?
Essentially they are not holding the call in que. Once switch to the hybrid (older Telos unit); the calls are dropped. I spoke to an engineering friend who states he has had the same trouble with VOIP doing the same thing. I may try and jerry-rig a phone with handset capabaility; ie speaker to mixing console, mic to mixminus.

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Re: VOIP lines w/ Tele Interface

Post by Tim Burke » Fri Feb 06, 2015 6:41 pm

Edit: Moved to On-Air Studios forum.

What are you using to connect the interface to your VoIP service?

duckfan98
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Re: VOIP lines w/ Tele Interface

Post by duckfan98 » Fri Feb 06, 2015 6:45 pm

What are you using to connect the interface to your VoIP service?
Here is the entire 'phone chain':

CallCentric VOIP service (provider) -> Network Switch -> Linksys PAP2 -> Phone Flasher Strobe -> Telos One -> Phone / Console

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Shane
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Re: VOIP lines w/ Tele Interface

Post by Shane » Fri Feb 06, 2015 11:57 pm

Don't you need some kind of analog port that looks to the hybrid like a telco line? Or is that what the PAP2 is?
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Re: VOIP lines w/ Tele Interface

Post by Tim Burke » Sat Feb 07, 2015 9:53 am

Shane wrote:Don't you need some kind of analog port that looks to the hybrid like a telco line? Or is that what the PAP2 is?
Yeah, the PAP2T is a device that allows standard POTS telephones to be used on SIP.
duckfan98 wrote:CallCentric VOIP service (provider) -> Network Switch -> Linksys PAP2 -> Phone Flasher Strobe -> Telos One -> Phone / Console
Probably a stupid question but have you tried hooking up a regular phone to the PAP2T to see if the issue still persists? If the issue persists, it could be a NAT transversal or firewall issue.

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Re: VOIP lines w/ Tele Interface

Post by duckfan98 » Sat Feb 07, 2015 10:42 am

Probably a stupid question but have you tried hooking up a regular phone to the PAP2T to see if the issue still persists? If the issue persists, it could be a NAT transversal or firewall issue.
Yes the phones work fine. Even connected 'through' the hybrid they work fine. Its only when the hybrid is switched to place the caller 'on the air' that the calls are dropped. It's as if the hybrid wont hold the call for whatever reason.

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Re: VOIP lines w/ Tele Interface

Post by Dale H. Cook » Sun Feb 08, 2015 8:53 am

Have you called Telos support?
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Shane
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Re: VOIP lines w/ Tele Interface

Post by Shane » Sun Feb 08, 2015 10:09 pm

It sounds like you are only needing to work one phone call at a time. If that is so, you might try this:

-Answer the call on the telephone set with the set connected to the hybrid jack marked for such a unit (that is to say -not- the jack marked Line).

-Instead of putting the call on hold, just leave the phone off the hook. (This is the part that will only allow you to work one call at a time because you can't use phone to answer another line.)

-Now pick up the call on the hybrid.

We have a pair of Telos 1's in our production studio and this is how we operate them, the only real differences being: 1) we have two hybrids with two different attached phone sets, and 2) we are using this with actual POTS lines.

And a question: do you get dial tone if you just pick up the line with the hybrid? If not, it might not be presenting what the PAP expects to seize the line.

I'd be interested to know if this works because we will be doing something similar soon with this very studio and hybrids.
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Re: VOIP lines w/ Tele Interface

Post by radiowave911 » Mon Feb 09, 2015 5:34 pm

I'm not so sure the issue is with VoIP itself, but rather a function of the ATA you are using for the analog lines. Not all are created equal :D

I used a Grandstream already into a DH-20 without issue. My guess would be that the Telos is not drawing the current the Linksys wants to see, since the Linksys does not see the current it expects for an off-hook device being drawn, it drops the line. You might want to try a different ATA to see if it behaves better.
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Re: VOIP lines w/ Tele Interface

Post by Baylink » Fri Mar 13, 2015 10:14 am

Not to put too fine a point on it, but remember: a VoIP call coming to you *is already 4-wire*, by the nature of VoIP.

Why would you want to *combine the channels* only to have to take them apart again? That's what hybrids do: they combine or separate between 4w and 2w telephone circuits: they are a reaction to the stupid price differential between those two in classical telephony delivery. And they do it imperfectly at best.

Find a VoIP client that does multiline termination and can be practically used by whomever needs to use it, and put it on hardware that has decent audio interfaces, whether analog or digital. Yes, it will be a little different than what you're doing now, but it's likely the audio quality will be worth it in the long run.

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Re: VOIP lines w/ Tele Interface

Post by dbuckley » Sun Mar 15, 2015 4:54 pm

I also wonder about this.

Our little community station has a PABX that is natively ISDN and VoIP, connected to the phone service over ISDN lines, all of which is inherently 4 wire, for want of a better description. One of the two POTS ports on the back of the PABX is connected to Telos hybrid. All this stuff was bought new at the time of station installation a few years back, so my assumption has been that VoIP or ISDN "things" that connect phone to desk (avoiding the word "hybrid"!) either didn't exist or were too expensive back then, as opposed to the company who specified this stuff didn't understand the technology they were specifying.

Given the choice, why would anyone go 4 wire to 2 wire then back to 4 wire in the same building...? Two wire has zero advantage in this scenario, and plenty of minuses.

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Re: VOIP lines w/ Tele Interface

Post by Baylink » Mon Mar 16, 2015 7:38 am

Precisely.

Though the fact that the PHY on your internet uplink (ISDN) is 4W is pretty much a red herring in this conversation; if it were single-pair VHDSL, it would still be 4W from the viewpoint of the internet connection.

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Re: VOIP lines w/ Tele Interface

Post by dbuckley » Thu Mar 19, 2015 5:36 pm

The ISDN in this case is voice over ISDN, 2B+D, not voice over internet over ISDN. But yes, its almost an academic distinction, the key thing we are violently agreeing on is that there are separate paths for the audio in each direction, which back in the days of analogue, was called "4 wire", and when you've got separate audio paths, why the heck would you unnecessarily combine them back to a common path.

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