Can PIAF Sense when a Copper Line is in use?

[thewisp]

Hello!

I admin a public school district with 5 buildings. We are slowly moving to voip pbx's (PIAF Yay!).

At one location (Location A), there is a PIAF with 8 Zap lines. These lines are shared with the other building (Location B), which has an old digital pbx.

Heres the problem, when the LocationA PIAF tries to use a zap channel, it intrudes on calls all ready in progress in locationB!

My question is, is there a way to tell the PIAF to first check for a dial tone before using the channel?

This is going to get phased out, but over a couple of years.

Any suggestions would be awesome!

 

[tm1000]

Hello!

I admin a public school district with 5 buildings. We are slowly moving to voip pbx's (PIAF Yay!).

At one location (Location A), there is a PIAF with 8 Zap lines. These lines are shared with the other building (Location B), which has an old digital pbx.

Heres the problem, when the LocationA PIAF tries to use a zap channel, it intrudes on calls all ready in progress in locationB!

My question is, is there a way to tell the PIAF to first check for a dial tone before using the channel?

This is going to get phased out, but over a couple of years.

Any suggestions would be awesome!

It shouldn't be doing this. I have a digium card with 4 lines, if one line is in use (AKA no dial tone) then the card will move on to the next line.

What Card are you using for your zap lines

 

[dswartz]

i thought there was an issue?

It shouldn't be doing this. I have a digium card with 4 lines, if one line is in use (AKA no dial tone) then the card will move on to the next line.

What Card are you using for your zap lines

I remember seeing people complain that inbound and outbound calls could step on each other, which implies that the collision detection was due to the outbound dialing code using a zap group, and people suggested tricks like having the inbound and outbound calls use the lines in reverse order or somesuch. I always thought that was ridiculous, but was apparently a real issue. Maybe the firmware (or asterisk) has changed since then (several years ago) and it now works correctly?

 

[kenn10]

Heres the problem, when the LocationA PIAF tries to use a zap channel, it intrudes on calls all ready in progress in locationB!

My question is, is there a way to tell the PIAF to first check for a dial tone before using the channel?

Sharing copper lines between buildings is not going to work. Zap isn't smart enough to figure that out. You need dedicated lines in each building. Why not put all copper lines into the Asterisk and have remote extensions through terminal adapters (check out the Linksys SPA8000) for the other building? This can greatly speed up your consolidation efforts.

 

[jmullinix]

I have used several brands of TDM cards and have seen this behavior on all of them. Zaptel/Dahdi is not smart enough to know when a line is in use unless it is using it.

To do what you want to do will require the use of ATA's in the old building, or an in and out TDM Card, one with as many FXS ports as FXO ports. That way Asterisk is in control of all of the POTS lines.

 

[Alex728]

I think its only with later versions of DAHDI that the analogue channels are checked for battery voltage before dialling out - before that glare/collisions can and did occur.

Unfortunately as DAHDI doesn't yet work 100% with analogue lines in my country I haven't had the chance to test it or I would give more details..

TBH why not just use the POTS lines for inbound only and VOIP trunks for outgoing calls as an initial workaround?

 

[blanchae]

I wonder if running a T1 or E1 card to a FXS channel bank would solve this problem. Let the channel bank determine if the line is in use.

 

[kenn10]

If you were going to spend the amount of money to put in a channel bank, you could probably just replace the whole old PBX. You could certainly extend the LAN and put terminal adapters on it or IP Phones.

 

[phonebuff]

Good Morning,

I have a simular configuration where we have Centrex lines multipunched on the Telco Termination Block for a total of four possiable end points.

* Analog Handset
* Dictaphone Recording
* ComDial Legacy PBX
* Channel Bank / Redfone / Asterisk

Incoming we see ring on all the end points, and untill the ComDial goes away they answer Aastra through Asterisk, if it's down (an it has not been yet), then they use the old ComDial phones, and if it's down they use the Analog handset.. Hopefully the ComDial goes away soon.

But I tell you this because we spent a lot of time working on what answers when and looking at the issue of someone picking up a ComDial line to listen to an Asterisk conversation as well as collision dialing on the Asterisk.

We finnaly decided that dial collision was unavoidable even with capital Gn processing, unless we were to feed the ComDial from the Asterisk box which defeated the concept here, so we have a "sock" that goes over the ComDial handsets to keep people off, and since the first thing Asterisk does is "answer" a inbound ring we have a script they can run from their windows Workstations if they need to so that the channels in Asterisk are turned off and they can swap back to ComDial.

To address your specific issue, if you are comfortable with Asterisk, terminate your lines in it. Then use something like the Linksys SPA8000 or audioCodes MPX to pass dial tone to the legacy system. (Ring Groups could let an incoming line ring both systems).

You really didn't adress call routing so I don't know if you are looking for a ring in both buildings at the same time or if it's a roll over between a to b / b to a depending on what number is dialed. But using a VoIP trunk and telco based CFB / CFNA between the two buildings, you might also be able to make this work..

Good luck ---

Hello!

I admin a public school district with 5 buildings. We are slowly moving to voip pbx's (PIAF Yay!).

At one location (Location A), there is a PIAF with 8 Zap lines. These lines are shared with the other building (Location B), which has an old digital pbx.

Heres the problem, when the LocationA PIAF tries to use a zap channel, it intrudes on calls all ready in progress in locationB!

My question is, is there a way to tell the PIAF to first check for a dial tone before using the channel?

This is going to get phased out, but over a couple of years.

Any suggestions would be awesome!

 

[tm1000]

Oh!

I believe what everyone is saying of course because you have all have years of experience over me, but I posted what I posted because recently during the so-cal storms our copper lines where destroyed and when the office tried to dial out they got the "all circuits are busy now", so I figured the zap/dahdi cards knew when voltage was present on the lines?

 

[blanchae]

If you were going to spend the amount of money to put in a channel bank, you could probably just replace the whole old PBX. You could certainly extend the LAN and put terminal adapters on it or IP Phones.

You can pick up used AdtranTSU 600 channel banks for less than $200 on ebay. The prices are all over the place, there's good deals as companies upgrade their phone systems and the surplus equipment is put up on ebay by the installers rather than being thrown out. I have about 8 sitting in storage right now that I picked up less than $100 each. One of the ebay items describes it as a video multiplexor and it's going for $10

 

[blanchae]

I have an Adtran TSU 600e setup in my lab - T1 to PiaF. I just realized that it isn't the Adtran that is costly but the T1 card - starting at $140+!

Regardless, I can run a quick test next week to see if it can detect calls in progress.

 

[thewisp]

Thanks everyone for your posts!

It is not cost as to why we keep the old system in place, but fear of change, this must be 'proven' in smaller installations before I can install in the larger buildings.

I learned alot here.

Regarding using ATA's to run voip lines into the old system....these buildings are connected via a 5ghz wireless link, which is very-very good. However, If something happens and these lines are unavailable it will ruin the confidence factor of every putting Piaf into the other schools. For now I will just arrange the routes so that they will not step on each other until the majority of the lines are in use. In anycase, we only use the copper lines at the Piaf for outbound calls.

Thanks again!

 

[etech3]

There are a few possible ways of doing this as has been posted.

But start from the beginning:
Questions for thewisp:
It sounds like this is a campus setup (more than one building. Is there one NID (network interface device, one central point for lines coming in from the street)

You said 8 ZAP lines. So a total of 8 lines for both buildings?

All voice lines or does this include fax modem or alarm lines?

What do you have between the buildings? copper, fiber? Is there a network? Is the cable between the buildings private or owned by the telco?

The old pbx, does it have spare trunk or station ports?