Thursday, September 21, 2006

Phone problem found, but not solved

Siemens M75
I have been unable to send SMS through my phone for some time now, so if you've not received SMS from me for some time, you know why. Too lazy/busy to get my phone fixed, so I'm living with it. Should be fixing my phone this Saturday.. (I've been telling myself this for the past month or so. :| )

Anyway, I think I've found out why my phone can't send sms! It's because of a certain header attached to the outgoing message (virus??) which caused the message to be unreadable by non-robust sms applications.

If your phone can't read my sms, it's because the sms reader on your hp is clueless on how to handle this header, and simply throws an exception.

For those who can, it can either be because your hp is robust enough to recover from the error, or it simply can't be bothered enough to put a finger on the error (ignores header!).

Here's how I found out:
I sent a message ("Test") from my phone over to a GPRS modem and decipher the received data (which shows a lot of other information!):
SMS (RAW STREAM): 06915689450002440A9156393820140000609072818304230B050A03000408A8E5391D
Service Center Address: 6598540020
Destination Address: 6593830241
Protocol Data Unit Type: 68 <----- BUGGY :: Should by 4. An extra value of 64 denotes an attached header!
Reply Path?: false
User Data Header Indicator?: true
Status Report Indicator: false
More Message to send: true
Message Type Indicator: 0
Data Coding Scheme: 0
Service Center Time Stamp: 2006/9/27 18:38:40 (Time Zone:32)
User Data Length: 11
UDL Checksum: Passed

IEI: 0A <---- ID of the belligerent Information Element in header
IED: 000408 <---- Data of the belligerent Information Element

Message: Test

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