On Sunday 20 July 2003 21:05, [EMAIL PROTECTED] wrote:
> A hosted gsm modem based solution
> will be costing £1000-£2000 a year
Ouch ! I want to sell those :-)
> Well a little
> known fact about the GSM protocol is that it allows queued messages to
> be concatenated in the conversation between SMSC and Cell Phone.
Don't know much about the lower transmission layers, so he may be right - my
tests definatly show otherwise - we did some load testing on modems, and even
under heavy load, where its obvious the SMSC has several hundreds messages
queued, it still takes somewhere between 4 to 6 seconds per incoming message.
this of course gets more then doubled if you also try to send MTs on the same
link.
> If I remove the keepalive cmd command at least that will be one less at
> command the modem has to handle.
It should be possible to make the AT2 driver not send keep alives if it sends
SIM polling commands - it sounds reasonable to me so I'll do that unless
people object. comments anyone ?
I still think you're focusing too much on SIM polling : under most conditions
the modem should forward all incoming messages, as fast as they come, to
Kannel and you would have no need to poll the SIM card. besides being slower
then CMTI forwarding (even if you poll every second), SIM buffering also has
a problem resulting from the fact that Flash memory (used in SIM cards) has a
limited number of writes available : about 10000 writes per bit. by forcing
your modem to store messages on the SIM card, you shorten the life of the SIM
card until one day it will stop functioning. for any kind of heavy traffic,
you'd probably wont get more then several months of operation.
> + my modem says it supports xon/xoff
> software flow control so I might change the com port settings in my
> bios.
Have no idea what would that change (simply because I don't know - not because
I don't think it'll do anything).
> What gsm modem do you use out of interest?
I'm using Wavecom WM02D and M1200. used some sort of Siemens (M45 ?) in the
past, but didn't like it and its bulky so it didn't fit as nice as the
wavecoms on our modem rack. I also got several Nokia handsets to work as
well, but you really don't want to do that :-)
--
Oded Arbel
m-Wise mobile solutions
[EMAIL PROTECTED]
+972-9-9581711 (116)
+972-67-340014
::..
Atilla The Hun's Maxim: If you're going to rape, pillage and burn, be sure to
do things in that order.
-- P. J. Plauger, Programming On Purpose, p147
