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7.4.4
 
Support new Carrier Access Network 
If the CAN supports packet switching then it is supported by all the frameworks. 
However the binding between a new CAN and the framework may be unspecified by the 
framework and must be defined first. 
7.4.5
 
Port the service to a different framework 
All of the service designs use standard open protocols for communication with the nodes 
of the framework, which is a good basis for portability. 
But in the end it depends on the features and constraints of the target framework. If the 
target framework does not support these protocols then an adapter must be introduced 
to interoperate between the protocols of the service and the target framework. 
GPRS sets the least constraints to the protocols used by the service, since it only 
provides data transport. IMS on the other hand dictates most of the protocols used by 
the service. This makes GPRS the least common multiplier of the services and all of 
them can be ported to GPRS. 
7.5
 
Interoperability 
7.5.1
 
Send and receive messages with GSM SMS clients 
Since GSM SMS is a text based messaging service, at least for the end-user, multimedia 
content can not be sent directly. UP11 in Table 2-4 describes how TMMS messages with 
multimedia content are adapted to GSM SMS. This is equal for all four of our service 
designs. 
The difference between the frameworks is how routing from TMMS PR to GSM SMS is 
supported. In our service design based on GPRS the TMMS PR gets no support to 
interoperate with GSM SMS, and must provide such support itself. 
On the other hand IMS supports routing of TEL URI, and an IP-MESSAGE-GW node 
can be introduced which picks up messages with a Request-URI of the TEL uri-scheme 
and routes them to a GSM SMSC. 
Both the OSA API and the OSA Parlay X Web Service frameworks have methods 
available which the TMMS PR can use to send messages to GSM SMS clients. 

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7.6 Discussion: : Reliability 
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