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On 7/18/06, Juha Heinanen jh@tutpro.com wrote:
JF writes:
You can have pre-paid SIP services without PSTN.
why? i don't understand how anyone would subscribe to such a service. how many email services you know that charge by the volume of email messages sent?
SIP-IPTV perhaps. Why would PSTN calls be the only motivation for people to pay? When that becomes cheap or for free, people will continue to pay for access to content that matters to them, no? Following you e-mail analogy, you might subscribe to online magazines, delivered to you via e-mail.
Also, an IMS S-CSCF based on SER would require this in order to be fully compliant to 3GPP standards, but probably this is of no importance in the scope of this list.
3gpp uses "SIP" to implement a walled garden. again, i have seen very little interest for it in user community. they simply use their nokia e series phones as regular rfc3261 compliant phones, not 3gpp phones.
Of course, in a first phase carriers prefer to try out plain SIP and not go to full IMS. But when "carriers" (or you can say "SIP service providers") start needing to control resources consumed by SIP sessions in their network and need to come up with a flexible and cheaper way to roll out new SIP services, IMS was designed for that (well or badly, we're not discussing that). You might argue you can just use the Internet and don't care about QoS, but to access some services the Internet may not be good enough, yet... And then "SIP service" needs to be defined... it's certainly not just PSTN termination. Can be anything provided via a SIP infrastructure.
Maybe we're getting too off topic here... I don't want to get into IMS flame wars. I'm just saying some IMS concepts may make sense in "non-IMS" environments, especially when trying to provide (SIP) services in a flexible way.
JF
-- juha