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schivmeister

Developer/TU

From: Singapore

Registered: 2007-05-17

Posts: 971

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Cellular Modems: Differences in Initialisation and Performance

I have a Motorola ROKR E8 which takes quite a while to connect with wvdial. It's not even recognised as a valid USB Modem device in GUI networking tools (option to connect is greyed out; see comparison below). DMESG universally stops at loading the ACM module:

usb 1-1: new high speed USB device using ehci_hcd and address 17
usb 1-1: configuration #1 chosen from 1 choice
cdc_acm 1-1:1.0: ttyACM0: USB ACM device

The part where it takes anywhere from 10 to 20 seconds during connection:

--> Carrier detected.  Waiting for prompt.

However, with a different cellphone, the initialisation and connection are without any kind of delay. In environments where there's gnome-network-manager (or whatever that network thingy is in GNOME), I could go through the setup wizard and connect immediately. On my system, there's not a single second I have to wait upon calling wvdial. This is a Nokia 5310 XpressMusic.

To my knowledge, both phones have the required hardware features to function as modems. The Motorola has Class 12 EDGE, while the Nokia has Class 32. I've found no details on the differences between those classes, but I'm confident they're not important variables in this case. If anything, the network speed of one may be slower. However, I don't see a reason why one would take so long to initiate if Linux is using generic drivers (cdc_acm). Interestingly, the Nokia's DMESG adds a little more after being recognised as a USB Modem.

usb 1-1: new high speed USB device using ehci_hcd and address 18
usb 1-1: configuration #1 chosen from 1 choice
cdc_acm 1-1:1.0: ttyACM0: USB ACM device
usbcore: registered new interface driver cdc_ether
usbcore: registered new interface driver rndis_host
usbcore: registered new interface driver rndis_wlan

Are those being registered because:

(1) The Nokia 5310 XpressMusic (or such Nokia phones) is in the list of supported devices and the Motorola ROKR E8 is not?

OR

(2) The Nokia 5310 XpressMusic (or such Nokia phones) has something more than the Motorola ROKR E8?

If it's (1),  I can hopefully contact the kernel list and inform them about it. If it's (2), what technical details should I be looking for? I know it's a bit of a stretch, but you don't have to help me

Last edited by schivmeister (2009-04-07 23:00:01)

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I need real, proper pen and paper for this.