Seeking advice: POTS for remote office, or 2nd Internet connection
Submitted by KodaK on Thu, 03/13/2008 - 2:32pm.
Ok, here's the deal:
I'm concerned with two locations. St. Louis is our main office, with around 20 or so people. We have a dynamic 3Mb connection, but we're hosting our own mail and web services (amongst other services.)
Our Kansas City location is down to one user at the moment, they've got a 3Mb down, 512kb up DSL connection. As I type this the latency to that phone is 200ms, but it's usually below 150ms (but not by much, most spot checks are around 140ms or so.)
I'm trying to decide if I should just put a small system in KC with POTS lines or if I should get a separate Internet connection in St. Louis solely for VoIP.
We are having quality issues with KC, and I strongly suspect that it's due to bandwidth contention on the St. Louis side. I've re-configured my network as much as is possible, really, and QoS just isn't cutting it -- I get a lot of email (and reject most of it as junk... :/ ) and I think that that traffic is causing most of the headaches. (And I mean a lot.)
Now, to throw more confusion on the fire: it's really more locations than that. I've got an office in Chicago, and several users that connect from home. A second internet connection would solve the local contention issue for all locations, but relying on best effort delivery may bite me in the ass. As I said, I strongly suspect that that's most of my issues, but I've got no guarantee that doing this will fix them, due to the open Internet transport.
As far as local service goes, I've already got a local PRI in Chicago, but the home users are just connecting over the Internet (as well as, of course, KC currently.)
So, what would you do in this situation? I see pros and cons of both options. I realize there are others, but these two are the only practical ones for the time being (IE: no MPLS between locations -- it's not cost effective for the number of users involved.)
Also, if you could share your "over the Internet VoIP" stories I'd be glad to hear them, I plan on pointing my bosses at this thread so they can see firsthand what your responses are.
Thanks.
I would first try using g729
Thu, 03/13/2008 - 3:04pm
I would first try using g729 for the remote users.
I have a client with about 4 locations and a 1.5 MB SDSL connection where the trixbox is located. The remote phones connect using g729, but use a regular ulaw sip trunk for incoming/outgoing calls (which is not a problem at all.)
Before we had those remote extensions on g729, they would often complain about quality issues. Now they dont. It is very very hard to realize that "voice quality drop" with digium's g729. The first time I tested the phone, I thought g729 didnt install properly but when I went to 'sip show channels' I saw g729 being used.
If g729 isn't an option in the St. Louis office, I guess using POTS would be acceptable.
I appreciate the suggestion,
Thu, 03/13/2008 - 3:18pm
I appreciate the suggestion, but g729 is out. I tried that. We've got Aastra 480i phones at the remote end, and they can only do one g.729 stream at a time and the user over there insists on having the option to answer all inbound calls (all other calls go direct to voice mail.) Also, I did run it for a while, and they claimed that g.729 made no difference in quality. I have no way of verifying that.
I proposed upgrading the phones in KC to something that can handle multiple g.729 streams, but I guess that got shot down because I didn't even get a response to that suggestion.
Feel free to keep suggesting, but chances are I've already thought of it and either dismissed it or had it dismissed by my bosses (usually due to cost.) But please don't take that to men "I don't want to hear it" because I do, I just want to explain beforehand why I may say "suggested it, got shot down." :/
FWIW, I'm running g.729 to the home users and gsm over the trunk to Chicago.
i dont think the bandwith is an issue
Thu, 03/13/2008 - 4:07pm
I am not as experienced as you KodaK by any stretch of the imagination. I can, however say that i have stretched the trixbox around the world and use it daily with very few if any problems outside of the ones generated by my lack of expertise. My apartment is connected to the system remotely thousands of miles away - has a standard dsl (1m down and 500k up) line. I can watch my slingbox tv setup and talk on the phone fine with - no problems with either. ( i am using ulaw for all communications by the way. not the most condensed but certainly clearest to my knowledge. I am pretty sure that a ulaw call will only utilise approx 64kb both ways .)
I have connection to my other place in Europe as well as my place stateside and from time to time connect from Europe to a remote unit in California. My weakest link is only one of the four service providers i use for outside lines and that pings at 120ms. My remote phones often ping at up to 400ms, however when speaking on them (internal to internal) they are clear as a crystal wine glass being jingled by a spoon handle preceeding a toast -- much more clear in fact than a regular pots call (no trixbox system but Bell with normal non cordless phones) between the same two locations (we tested that before installing the voip). When using the high pingtime phones on outside calls, they are usually as good as the providers line.
I do, however use all cisco phones. I have not ever to my recollection had any experience with degradation of call with the exception of having that same one provider improperly configured - which was quickly remedied and of course my fault.
I can not believe, although i understand it is in fact possible, that the internet would be to blame for the poor call quality given that my system provides an extreme case and i test it hard every day of the week - with real use keeping the telemarketers believing that i am actually at home in each place all the time.
If you want to pm me with a number, im abroad now and would be happy to put a call through to you to give you a feel for the clarity from the other side of the world - if that helps.
All remote offices (barring
Thu, 03/13/2008 - 7:42pm
All remote offices (barring home users) are already connected via VPN, and QoS is already implemented on those links. The problem exists (I believe) in the DMZ, where I'm getting hit with lots of web and email traffic.
I'm not kidding about that. I'm pulling thousands of messages a day across a 3Mb link, and those (nebulous) numbers are only after I reject based on various black lists and pre-greeting traffic and other "HI I AM A SPAM BOT" checks. I reject probably 2/3rds of the mail I'm receiving, and a lot of the legitimate stuff that we do pull in is multi page PDFs with appraisals and rate sheets and the like.
I'd love to host this elsewhere, but when it takes my users longer than 5 seconds to send a 400 page PDF to the mail server it's "slow." Although I suppose I could still have an internal mail server to queue things up, then send it out slowly. Something to think about.
This may look familiar to some people (with a small change):
Internet<-->Telco router<--->border router<-->int phones/computers/etc
|
|
v
DMZ:Mail/Web
The link into the border router is saturated because of web and mail (and scp and PPtP and and and. . .) traffic going to the DMZ. It doesn't matter what type of QoS I put there, because I can't control what's coming in only what's going out.
Try the iLBC codec!
Fri, 03/14/2008 - 5:09am
The Asterisk servers in our offices were connected using VPN and QOS features of our routers, and that helped but didn't really do the trick. I had read that the iLBC codec handled missing and delayed IP packets better than other protocols, and while not as low bandwidth as g729, it is only about a third of the bandwidth of ulaw/alaw. Changing the servers' IAX connections to use the iLBC codec has worked well for us. Haven't had any complaints, only compliments so far.
I could give iLBC a shot on
Fri, 03/14/2008 - 6:34am
Are you sure the KS phones don't support iLBC?
Fri, 03/14/2008 - 7:36am
Perhaps I should have also mentioned that we have people using remote extensions to the offices that are softphones that support the iLBC codec. They work better using that codec also. Maybe you would have made the connection then, or perhaps, you already knew that the KS phones didn't support the use of that codec.
Member Since:
2006-06-14