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4.2.6.3
 
Charging Request Not Accepted 
This subsection applies to both section 4.2.6.1 and section 4.2.6.2. 
If the client returns 606 (Not Acceptable) that means the client does not accept to be 
charged. Hence the TMMS PR sends a Sh-Update request to the HSS which deletes the 
message. The figure below shows this. 
Figure 4-17: IMS online charging, client declines to be charged 

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4.3 TMMS Service based on IMS: : Evaluation 
Page 61 of 93 
4.3
 
Evaluation 
4.3.1
 
Security 
Table 4-1: Evaluation of Security quality attribute for TMMS Service based on IMS 
S1: Service is available for legitimate use and sustains Denial of Service attacks 
Availabili
ty
 
Service gets available to users through updating their Service Profile GUP and 
iFC to include TMMS PR 
S2: Data is not altered during transmission 
In
tegr
it
y 
IMS uses IPSec and the ESP protocol to ensure integrity. 
S3: Sender and receiver confirms that they are who they claim to be
Authentication 
IMS Specific. The service must trust that the IMS network already has 
authenticated the users of the service. 
S4: Only authorized users get access to the service 
Authori
zation 
Through Sh interface the service can check with HSS if a client is authorized. 
S5: Only sender and the intended destination part is able to know the content of 
the message 
Confidentiality 
IMS uses IPSec to ensure confidentiality. 

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4.3 TMMS Service based on IMS: : Evaluation 
Page 62 of 93