Bradley Hook bhook at
Fri Apr 6 21:18:59 CEST 2007

Jonathon Suggs wrote:
> Tim Newsom wrote:
>> That seems weird... Even in email you can turn off read receipts... It
>> seems like an invasion of sort (though a minor one) to not allow
>> disabling of delivery reports for the receiving party.
>> If the sending party can enable it and the receivers phone
>> automatically responds, then you can always know when someones phone
>> is turned on/available.
>> Does the sms message system work while the phone is in call mode? Does
>> that require multiplex code also like the gprs while on a call does?
>> If it doesn't work while calling, you can always find out when someone
>> is done talking on the phone / is available to talk (assuming they are
>> at the phone) by sending an sms with delivery report first... Right?
>> Seems like there should be some kind of control message that could be
>> sent over the serial port via 'AT' commands which would enable and
>> disable this.
>> --Tim 
> Ok, I'll be honest that I have no proof that this is how it actually
> works, but I don't think it works the way you are saying it does. 
> Again, not 100% positive, but the "receipt" that you receive is only a
> message that it has been successfully transfered to the carrier.  The
> carrier will then try to push the SMS to the recipient whenever they
> become available.  So there are two discreet actions.  1) Transfer from
> sender to carrier 2) Transfer from carrier to destination.
> Rather than get all worried about big brother, just do a simple test. 
> Turn off a phone and send a text message to it.  See if you get a
> receipt.  If you do, then I'm right.  If you don't get a receipt until
> the phone you sent a text message to is turned back on THEN commence the
> meetings of the tin foil hat club.
> -Jonathon

SMS most likely uses a mechanism similar (or identical) to the ESMTP DSN
model. See for more info.

With cell phones, it seems that the destination storage medium for the
message server is the phone itself. The phones probably don't get any
headers on the message in advance of accepting the message, so there is
probably no way to reject messages on a per-sender basis, at least not
in a way that avoids being charged for message delivery. As long as Ma
Bell controls the message servers, we probably wont have a way around this.

You could probably implement a "Reject All" feature by simply refusing
to accept transmission of SMS messages. This may be desirable for people
that don't like receiving text messages at all (i.e., me).


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