Most of my response to this has already been captured in some form by Kristian and Ken, but just to sum up:
1. I didn't say that these types of signaling errata don't occur. They do. They should be treated as a cost of doing business. If they account for a nontrivial percentage of lost revenue, you've got a more fundamental problem of a technical nature somewhere and need to fix the problem at the source. The lost money should be utterly trivial in comparison to the amount of money you would need to spend to handle all media from customers in a way that is reliable, scalable and reasonably mitigates QoS issues. Scalability is probably the biggest cost, even though it is not visible as an immediate, short-term cash outflow. As with most other things in business, it needs to be Pareto-optimal. 2. As Ken alluded, if you have a nontrivial amount of such occurrences, there is most likely a technical problem somewhere. You, your vendors, or your suppliers are doing something wrong. SIP signaling is not inherently flawed in its relationship to accounting, or exceptionally unreliable compared to other signaling technologies where the transport and switching assembly entails a separate signaling and bearer plane. SIP does have reliable retransmission of initial and sequential requests as well as final replies, and they do work--if you're losing more than an infinitesimal fraction of them, you've got a network or equipment problem in the path. CPE disappearing due to shoddy power or connectivity can be mitigated through the use of session timers, as Kristian suggested. You need to figure out what the problem is. At the root of this, what I'm advocating is not a reckless disregard for cost control or billing discrepancies as much as it is a lean, fundamentals-based, back-to-basics, no-nonsense technical and backoffice process strategy. By the way, 179811 - 130740 is a difference of 49071. 249 / 49071 is an average per-minute rate of half a penny ($.005), so let's say for assumption's sake that the rest of your traffic (the 130k minutes) consists of $.005/min flat. That's $650, which means your overage is 38% of the rest of your gross. If you have that kind of billing errata, you've got far, far more fundamental issues per million than random CDR slips due to missing signaling in normal operating conditions should produce. While nobody knows what that exposure figure is, it shouldn't be ~25% of your bill! I've successfully set up SIP-only usage accounting for an operation that does over 3 million minutes a month, and their discrepancies with their upstream carriers (yes, they use SIP trunks) average an error margin of maybe 1.2%. Now, this is a viciously thin-margin space, so really, 1.2% is too high and I'm trying to get that corrected for them. I should follow my own advice. -- Alex Nitzan Kon wrote: > --- On Sun, 1/4/09, Alex Balashov <abalas...@evaristesys.com> wrote: > >> Many of them have claimed they lose a ton of money from >> accounting problems caused by the unreliability of signaling >> (as though SIP doesn't have reliable retransmission of transactional >> messages or something) but they've never shown me any numbers to >> substantiate that. > > OK, here's some statistics for the month of December for > the carrier in question: > > Our record shows: > 100,504 calls > 130,740:27 minutes total > > Their record shows: > 100,161 calls (probably just time difference here > 179,811.28 minutes total > > Their record shows total rate charged $229 higher than what > our billing system determined we SHOULD have been charged. > In other words- $229 extra have been charged due to signaling > problems - and this is just one month. > > I used to ask them for refunds for these but to be honest it's > such a PITA that I just gave up and started routing most of > our traffic to other carriers. > > Bad billing is bad for business no matter how great your > call quality is. :) > > -- Nitzan > http://www.comparevoipproviderrates.com/ > > _______________________________________________ > --Bandwidth and Colocation Provided by http://www.api-digital.com-- > > asterisk-biz mailing list > To UNSUBSCRIBE or update options visit: > http://lists.digium.com/mailman/listinfo/asterisk-biz -- Alex Balashov Evariste Systems Web : http://www.evaristesys.com/ Tel : (+1) (678) 954-0670 Direct : (+1) (678) 954-0671 Mobile : (+1) (678) 237-1775 _______________________________________________ --Bandwidth and Colocation Provided by http://www.api-digital.com-- asterisk-biz mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-biz