Posts by David Thorn 11 publicly visible posts • joined 29 Apr 2008
Yes - it always was 140 bytes, which when using 3GPP 03.38 7 bit encoding allowed you to fit in 160 characters. The reason for the limit was the max size of an SCCP packet being 255 bytes, which once removing all the header, routing and transactional data should leave you with at least 140 bytes.
Unfortunately the standards then introduced application contexts which added more data meaning that long text messages no longer fit in a single packet, but hey ho, that's life.
There seems to be all sorts of speculation here about how it is charged for but surely the easiest way is to just use one and see what happens.
Like this:
Fare Breakdown
CHARGES
Base Fare £3.00
Distance £1.92
Time £1.30
Charge subtotal £6.22
DISCOUNTS
Rounding Down -£0.22
Discount subtotal -£0.22
TOTALS
Total Fare £6.00
Amount Charged -£6.00
Outstanding Balance £0.00
Trip Statistics
DISTANCE
1.30 miles
DURATION
7 minutes, 15 seconds
AVERAGE SPEED
10.76 mph
It's not a "Subscriber Identity Module" as all it's doing is using the SIM Application Toolkit commands to intercept the dial request and presumably dial an indirection service first.
If you note their tariffs are all plus your normal calling plan and require your number not to be witheld so you're using your normal SIM identity.
Their international piece is slightly more interesting in that it seems to be an automated callback but again that can be done using the call control features (ie auto answer when the callback occurs) of the STK.
The article imples that being able to instruct the handset to treat an SMS as Internet Electronic Mail is a relatively recent addition to the 3GPP specifications. It's certainly been in the specs since 03.40-540 (late 1996?), but that's the earliest one I have to hand...
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