[Asterisk-Users] Small office setup/using analog lines w/ Ast erisk

[Colin Anderson]

>The Digium cards actually are sharing IRQs with other devices -- the 
>installer mentioned it could be an issue initially, but when he saw that 
>the devices that the cards were sharing with were the network card and 
>the video card, he said to just try and see if it works first. Sounds 
>like some of the problems that we're having could be related to this, 
>and it's probably the first thing I should try changing.

Definitely sort out the IRQ problems first. Absolutely, the TDM cards
require a distinct IRQ. Disable every onboard device if it isn't needed
including USB, sound card, parallel port, serial port, etc (to give you more
IRQ choices). Run /usr/src/zaptel/zttest before and after and see if it
makes any difference. If it does (i.e. ZTTEST yields ~98.X% before and
~99.X% after) then right there that's going to help.

I have used these statements in /etc/rc.d/rc.local to good effect (YMMV)

setpci -v -s 01:04:0 latency_timer=ff <--Specific statement for Digium
TDM04, you will have to do lspci -vv for the pci vendor id of your specific
Digium card

setpci -v -s XX:XX:X latency_timer=0 <-- Replace XX:XX:X with the PCI Vendor
ID of every other card that lspci -vv recognizes. 

What the setpci statements do is allow the Digium cards to hog the bus more
than any other card. It is controversial as to whether this actually does
anything; some guys claim not, however, it worked for me. 

>If the sound quality is poor, I'll try hooking up the phones to 
>a new network card.

Um, yup. In fact, I'd ditch *any* embedded NIC unless it was eepro100 or
3com (not very common these days) 'cause
embedded these days is pretty much crapola. 

>One additional question -- are VoIP lines generally easier to get going 
>w/ good sound quality than POTS lines? 

Yes and no. They are different animals. Asterisk bridges the two, but the
kind of latency/ echos / bad call quality etc issues are on the same order
of magnitude for PSTN and VoIP. They just require different methodologies
and training to troubleshoot. It's easy to set up a crappy VoIP link. 

>Another thing I was wondering is 
>whether we could get hunting to work properly with a mix of VoIP and 
>POTS. I'll call the phone company tomorrow, but if anyone has tried 
>anything like this, I'd like to hear about it.

This is all dialplan stuff. A crude way to do it is to set your
extensions.conf to Dial(ZAP/g0/xxxxxxxx) to use your PSTN lines and to
Dial(IAX2/foo:1111 at somewhere.com) as the next priority, so if all of your
ZAP channels are busy, it will dial IAX/SIP after the ZAP priority fails.
Problem there, is for inbound calls. In this scenario, if you have your
inbound number that rings to a ZAP channel, a caller will ring busy if the
zap channel is in use. If that works for you, fine. If not, you could work
with this scenario by having all of your inbound numbers come in thru a VoIP
provider and all your outbound thru ZAP with a failover option to IAX2/your
provider if the zap channels were all busy. If you want to get fancy, some
providers will failover to a PSTN number of your choice if your server is
not responding. 

The nice thing in this scenario is that an IAX or SIP provider changes the
definition of what a "line" is so theoretically you can have hundreds of
simultaneous inbound "lines" if you want, you just pay per-minute charge X
number of simultaneous inbound "lines". This functionality is per-provider,
they all have different policies. 

>Oh, great. ;-) For next time, does anyone have recommendations for a 
>particular motherboard or a particular type of motherboard?

Yup. Intel chip. I know people will say I'm trolling, but I wouldn't use an
AMD for an Asterisk box. Workstation, yes. I run one myself, they work fine.
Note I said Chip not Chipset. I've had good luck with older Intel chipsets
but from what I understand some other guys have had problems with the new
Intel chipsets. I totally trust Asus though. What I would do were I you is
Asus with no onboard stuff as much as possible with a P4 chip. 

>This is for an office -- I figured that running hardware RAID would be 
>the most likely to avoid downtime if a hard drive failed. How do most 
>people handle this?

You don't. You do not use hardware RAID on an Asterisk box, and if you do,
you try it beforehand. Interrupts. All about the interrupts. As a point of
reference, our extremely expensive Mitel ICP 3300 has a 20 gig Maxtor in it.
That's all. Same hard drive as a friggin Xbox! 

Strategies for recovering that I would look at if you want to try sans RAID
is to do your Asterisk config, then ghost it onto a second HD, then install
the 2nd hard drive as a warm spare with an IDE drive carrier (this is a tray
that is removable like a SCSI hot swap, except not hot) and every night you
cron a 'dd' command to dupe the primary HDD onto the spare (dd application
note: make damn sure that the spare drive is the exact same model. dd will
not compensate if your drive has different geometry). Primary fails, turn
off the box, yank out the primary, move the spare to the primary, turn on
box. Worst case scenario is that you loose X hours of voice mails and call
logging where X is the number of hours since the last DD command. 

One last comment: TDM04 cards have to be reinitialized periodically
otherwise they sound like crap. And by reinitialized, I mean warm boot.
Maybe Digium fixed this, but mine, I reboot the boxes every night. No more
problems. 

hth, keep the faith. Once it working good you will never go back and laugh
at everything else.