[Kamailio-Users] prepaid system

Alex Balashov abalashov at evaristesys.com
Tue Dec 30 13:42:58 CET 2008

It's a good thought.

My concern is that from an economic perspective, coming up with any 
grand, unifying schemes or projects to solve these architectural 
challenges is mostly a pointless waste of time.

While admittedly the prepaid model is proving to be quite a viable 
inroad in many parts of the world outside of the US and W. Europe (and 
indeed, much of the interest seems to be there), fundamentally it can 
only exist to the measure that:

(1) Voice switching, transport and subscriber services are billed by 
per-minute usage, and voice infrastructure and service delivery systems 
are monetised this way;

(2) The process of rebilling for usage is a derivative function of the 
economics of PSTN interconnection and how the PSTN TDM carrier-world 
business model works (a series of billable events and relatively fixed 
reservations of capacity) versus the Internet business model (primarily 
flat-rate peering and settlement-free peering among backbone haulers) 
that revolves around higher-order applications delivered over packets;

(3) There are not too many flat-rate alternatives available elsewhere in 
the telecom world.

I think #3 is the most important and the one that is likely to prove 
most relevant in the short term, as I think we can all agree that there 
is no expectation that the PSTN in a time frame anyone would deem short 
to immediate term.

For example, here in the US, pre-paid calling cards are largely obsolete 
and highly irrelevant from a mass-market perspective.  They survive in 
various niches where people remain that are somehow sentimentally or 
inertially attached to calling cards and fixed-line long-distance;  this 
includes retirees, large communities of first-generation immigrants for 
whom this is a viable means of making calls to their home countries 
relatively inexpensively, and so on.  But really, by and large landline 
revenue is falling precipitously, everyone has a mobile, international 
rate plans are available for those who truly need to make a lot of 
international calls, and domestic long-distance is increasingly 
flat-rate / unlimited on fixed-line (and is already so on mobile).

For the most part, people ordering origination (DIDs) in the form of 
wholesale trunking are interested in flat-rate DIDs as well. 
Termination will remain usage-based, but only so far as points #1 and #2 
above are highly operative, and only so long as private VoIP peering 
doesn't gain any serious traction.

All these details can be debated at great length, but the salient point 
here is that this is a business model that is intimately bound up with 
the idiosyncrasies of the PSTN and the way the incumbent voice business 
has functioned for almost a century.

It is fairly obvious, I think, that whenever it is that we do get around 
to moving beyond the PSTN, in part or in whole, the centrality and 
unassailable importance of "minutes" as a billing fixture will be 
expected to disappear in line with the ontology to which all other 
Internet-based application services are subject.  Meanwhile, the 
incumbent telco world will go increasingly to flat-rate and unlimited 
plans and there will be continuing downward cost pressure, as well as 
increasing local loop deregulation and unbundling in a variety of other 
national markets in which state incumbents persist with varying degrees 
of success.

So, while this sort of stuff can probably make a decent amount of money 
in the US and Europe if appropriatedly positioned/marketed/specialised, 
and certainly can work in Latin America, the Middle East, etc., it does 
have the quality of being somewhat regressive and not particularly 
forward-thinking.  It is overly connected to a shifting and unstable 
landscape of arbitrage opportunities arising from the position of VoIP 
relative to the PSTN and wireless;  specifically, that most calls still 
terminate or transit the PSTN.

That's why I think a large, consolidated open-source effort to build a 
highly complicated, robust prepaid service delivery platform from 
components like Kamailio/OpenSIPS is largely pointless.  Otherwise I 
would be the first to lend it my enthusiasm.

Luciano Afranllie wrote:

> On Tue, Dec 30, 2008 at 9:44 AM, Peter Lemenkov <lemenkov at gmail.com> wrote:
>> Hello!
>> 2008/12/29 Daniel-Constantin Mierla <miconda at gmail.com>:
>>> Hello,
>>> On 12/29/08 13:51, Peter Lemenkov wrote:
>>>> [...]
>>>> * At the time of user calls somewhere, we (after checking its auth
>>>> data) rewrite its URI using custom plugin for OpenSER (which utilizes
>>>> libsqlora8 library). It's not a rocket science, and (in simplified
>>>> form) it looks like the following:
>>> Is libsqlora8 working with latest API libs from Oracle?
>> Yes. We use it in conjunction with Oracle 10g.
>>> When I checked the project looked dead.
>> I would say that libsqlora8 is finished :) - it works well and
>> therefore doesn't need to be updated.
>>> From 1.4 on, there is a dedicated driver for Oracle. Have you tried it? I
>>> wonder what is the maturity of that module.
>> No, we haven't tried yet.
> I don't know if this has been discussed earlier but it would be nice
> to point some key requirements for a system supporting prepaid users
> and possible solutions to those requirements.
> I think several of us is doing the same things so, we can benefit from
> other experience and may be we can find a pattern (of course not
> perfect and "fit all") for this problem using open source
> alternatives.
> I am talking about something like this:
> - How to store and retrieve user category (postpaid, prepaid, etc).
> LDAP, Radius, SER groups?
> - Callflows
> - What IVR to use for user notifications (no credit, etc) and user
> balance check?
> Asterisk, SEMS, etc?
> - How to enforce call tear down when credit is exhausted?
> What B2BUA to use?
> - How to manage recharges?
> Etc, etc.
> Regards
> Luciano
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Alex Balashov
Evariste Systems
Web    : http://www.evaristesys.com/
Tel    : (+1) (678) 954-0670
Direct : (+1) (678) 954-0671
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