[SR-Users] want to go mobile, common issues ?

Franz Edler franz.edler at technikum-wien.at
Sat Feb 27 08:28:00 CET 2016

Hi Sebastian,

> I have enjoyed talk about realtime of last FOSDEM, talk about K. was good.
> I want to know how do you solve sip dialogs with mobile? actually I know
> REGISTER is important to authenticate and this request generally last 1hour
> until then you have to register again.
> How to solve that for mobile telephony (and what about idle) ? do cellular
> phone use this schema ? you have to go UDP ? does TCP comes better to
> handle mobile telephony?

Yes, of course. But in the mobile world IMS (IP Mutimedia Subsystem) is used.
For registration IMS uses an advanced authentication scheme (IMS-AKA) which automatically sets-up an IPsec connection between the mobile and the P-CSCF (first nose of the network).

> I want to ask about IMS as well :-)
That is a huge architecture based on SIP. The main reason for this architecture is to give the operator control and responsibility about services, which is not possible with pure SIP.
Pure SIP follows the end-to-end model of the Internet with all responsibility on the host side, no need to provide additional services inside the network.

> I heard many good things about Image Multimedia Systems, but in concrete  terms what is it?
As above.

> Does IMS target mobile only ? 
No. The target is for fixed and mobile networks to use one common core based on IMS.

> I heard about Boghe, it has many more > parameters regarding DNS SRV and extra options. 
> What's so different from  my traditionnal Linphone ?
There are many more functions necessary for a true IMS client. Just look into RFC 7315 "3GPP SIP P-Header Extensions" for a first view.

BR Franz

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