Clarification needed on AT+CPMS

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agnelo@sasken.com - 08 Aug 2005 05:53 GMT

3GPP TS 27.005 states in section 3.2.2 that a possible response to
"AT+CPMS?" is
+CPMS:
<mem1>,<used1>,<total1>,<mem2>,<used2>,<total2>,<mem3>,<used3>,<total3>

The parameter <used1> is defined in section 3.1 as
<used1> integer type; number of messages currently in <mem1>

What is not very clear to me is whether <used1> stands for the total
number
of messages in the SIM or the total number of message locations in the
SIM that are used.

Can someone please clarify?

total number of messages in SIM <= total number of used message
locations in SIM

In the case where a large SMS is split into several segments the number
of msgs in SIM will be less than the number of used msg location in the
SIM.

The literal meaning of the parameter <used1> seems to suggest that it
is the total number of messages in SIM and not the total number of used
msg locations in SIM. But what purpose would it serve to return the
total number of messages in the SIM?

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John Henderson - 08 Aug 2005 07:18 GMT

> 3GPP TS 27.005 states in section 3.2.2 that a possible
> response to "AT+CPMS?" is
> +CPMS:

> The parameter <used1> is defined in section 3.1 as
> <used1> integer type; number of messages currently in <mem1>
[quoted text clipped - 17 lines]
> would it serve to return the total number of messages in the
> SIM?

I'd be absolutely confident that it's the "number of used
message locations" (to use your terminology). Realistically,
"AT+CPMS" can have no understanding of the mechanism by which
atomic messages get assembled into a larger message spanning
more than 140 bytes (or 160 7-bit characters). That's done at
a higher level than the PDU layer where "AT+CPMS" can operate.

If a large message is split into 3 for example, that's 3
individual and completely separate messages as far as any
transport or storage layer is concerned. It's reassembled only
when viewed at the "man-machine interface".

GSM devices are required to store messages "as received".

John

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John Henderson - 08 Aug 2005 08:03 GMT

> What is not very clear to me is whether <used1> stands for the
> total number of messages in the SIM or the total number of
> message locations in the SIM that are used.

Easily demonstarted by experiment:

AT+CPMS?
+CPMS: "ME",13,100,"ME",13,100,"ME",13,100

Then store a 2-part SMS, and repeat the query:

AT+CPMS?
+CPMS: "ME",15,100,"ME",15,100,"ME",15,100

John

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agnelo@sasken.com - 09 Aug 2005 06:10 GMT

Thank you very much John.
I actually need to implement the AT command.
What hardware/phone did you test AT+CPMS on?

Agnelo

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John Henderson - 09 Aug 2005 06:44 GMT

> Thank you very much John.
> I actually need to implement the AT command.
> What hardware/phone did you test AT+CPMS on?

The test was on a Siemens S55. This is a PDU-mode phone
("AT+CMGF=1" is not supported).

John

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