The real question here is - is there a better newsgroup or yahoo group or anything to ask this question on?
We use a Wavecom modem to transmit a TCPIP link over GPRS.
We work with Linux, and use the TCPIP stack inside Linux. I know some modems have a TCPIP stack of their very own, but we consider it would be too difficult to wean Linux off this and get it to use the modem's one.
While a TCPIP link is open, every byte sent to the modem forms part of that stream, and we can't send AT commands to the modem to ( for instance ) initiate/receive an SMS message, or ask the cell name, signal strength or anything. And since we try to keep the GPRS link open all the time, that's a bit of an annoyance.
Now.
Wavecom provide a command AT+WMUX, which changes the modem into a mode where all AT commands and data are encapsulated in little packets, and a flag is added to each packet saying "command", "data", "reply to command", etc. if we used this mode we could, in theory, have the best of both worlds.
Trouble is it looks like it would mean diving deep and dirty into the depths of Linux, and intercepting all uses of the modem, both in the CHAT session which opens + closes the modem, and the PPP s/w which sends TCPIP data. I'm not looking forward to that degree of surgery.
We don't really want to lock in to a single manufacturer, so if this is a feature which only exists on this one modem manufacturer's products, I'd be less inclined to do the work to use it.
I have a few questions then...
- Anyone done this?
- Anyone know if Linux by any chance already support this?
- Anyone know if this WMUX command is available on other modems apart from this Wavecom one?
- I'm aware that there exist modems with a second serial port which could help with this, but that looks to me like yet another avenue to locking in to a subset of modems.
- Any better suggestions?
David Collier
email can be sent to Dexdyne.com , under name from_usenet@