Preparing and sending SMS messages with the intention of asking/requesting something in anticipation of a response naturally requires a reply address. iPhone, according to pod2g has the ability to alter the reply address. Subject to the known variables in a 'stored evidence' check list this could have an impact on the initial assessment and interpretation of evidence for certain types of evidence from/to mobile phones.
This will put a strain on resources linking the chain of causation, which will need to be minimised. Having a 'stored evidence' check list can help you do this.
Not mentioned in the article is the position for a user to add a reply-path for different Service Centres, and naturally we have are aware of websites that allow spoofed originating addresses.
Moreover, when checking the SMS header details do remember to check
Originating Address type 91
Type of number International
Numbering plan identifier E.164
Originating Address 44798021XXXX
and where you see 'Originating address' that does not contain the commonly understood mobile telephone number (E.164) but it contains an hex-decimal representation then it might indicate the message originated from the internet. Example
Originating Address type 91
Type of number International
Numbering plan identifier E.164
Originating Address 35fac2457c0be2008
To start with go back to basics (this is necessary due to the requirements of backward compatibility) and check out GSM standards GSM-0340; 0338, 0411, 0902 etc
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