Interoperability Between Machine-to-Machine Communication System and IP Multimedia Subsystem - Interoperability and Open-Source Solutions for the Internet of Things - page 112

I MS UAA P-CSCF I -CSCF S-CSCF HSS MTAS/AP

AA GSCL

HTTP

1:UPDATE (PUT)
alarm on
2: STATUS-OK (204)

3:NOTIFY (POST)
alarm on
4 : STATUS-OK (204)

SIP

5: REGISTER

6: REGISTER

7: UAR
8: UAA

9: REGISTER

10: MAR
11: MAA

12 : 401 (Unauthorized )

13 : 401 (Unauthorized )

14 : 401 (Unauthorized )
15: REGISTER

16: REGISTER

17: UAR
18: UAA

19: REGISTER

Authentication

20: SAR
21: SAA

2 2: 200 (REGISTER)

2 3: 200 (REGISTER)

2 4: 200 (REGISTER)

25: REGISTER
26: UDR
27: UDA
28: 200 OK (REGISTER)

Fig. 7. Triggering IMS UA registration

22-24 The S-CSCF sends a 200 OK response to the UE indicating that the
registration was successful.
25 Register request is sent from S-CSCF towards Application Server (MTAS/
AP) for third party registration.
26 Application Server (MTAS/AP) further sends a User data request to
the HSS for retrieving the subscriber related data for telephony and
supplementary services.
27 HSS sends a User Data Answer towards Application Server (MTAS/AP)
containing user data details for supplementary and telephony services.
28 Application Server sends the 200 OK towards S-CSCF after successful
3rd Party Registration.

When somebody is at the door and rings the bell, door application (DA)
sends message to M2M gateway (GSCL) which starts the multimedia session
from intercom application (IA) to the user's mobile phone or any other IMS UA
that is defined in the application (see Fig. 8 ). The user is alerted that somebody
is at the door by an incoming call. The user can pick up the multimedia call on
the mobile phone that is running IMS client and talk to the person at the door
like he or she is at home (see Fig. 6 ). The multimedia session establishment is
comprised by the following steps [ 1 ]:

1 Door application updates (UPDATE) GSCL data that door bell is
ringing.