I have the "cannot open communication device" error on my TiBook 550 when I try to dial in. By looking in the console, i can see that the "dev/cu.modem" is busy. Well whats tying it up? I may have a clue. After trying to connect, a background application is started. By examining the process viewer, i see a background process called AppleModemOnHold. This name is highly suggestive. If this application is using the modem, that would prevent internet connect from using it (only one application can use a port, like the modem, at any given time). I then found an article on xlr8yourmac.com discussing a new 10.2 feature: Modem on Hold.
Here is the blurb:
Notes on Jaguar V.92 Modem Driver with Hold Feature, Supporting ISP Listing
" Apple has updated the modem driver in Jaguar to support v.92. This support also includes modem on hold which allows you to put your internet connection on hold to answer an incoming call. The Network Prefs/Modem panel (*on a machine with a supported modem*) shows several new options that pertain to v.92. The ISP also needs to have v.92 servers for this to work.
http://www.modemsite.com/56k/v92isp.asp lists the current ISP's that support v.92. The new driver also appears to fix the random disconnect problems users have reported on the Apple discussion boards. This update is for the internal usb modem only."
I think this feature has a bug that is playing up with the modem. I confirmed something that I had noticed before. Under my powerbook I see additional options under the modem tab. Things like what to do with incoming calls. This option is not shown on my quicksilver (which dials up fine). They are both apple internal modems, but my TiBook's one has these v.92 options. This is the only difference between computers that dial up fine for me, and computers that don't. Theres no way that is a coincidence.
I'm not sure how to proceed, but this does seem like the probable cause. Please post if you have similar issues, and if you see this AppleModemOnHold app running after you attempt to dial. I see no mention of this being fixed in the 10.2.1 update, so if your effected, post here.
Here is the blurb:
Notes on Jaguar V.92 Modem Driver with Hold Feature, Supporting ISP Listing
" Apple has updated the modem driver in Jaguar to support v.92. This support also includes modem on hold which allows you to put your internet connection on hold to answer an incoming call. The Network Prefs/Modem panel (*on a machine with a supported modem*) shows several new options that pertain to v.92. The ISP also needs to have v.92 servers for this to work.
http://www.modemsite.com/56k/v92isp.asp lists the current ISP's that support v.92. The new driver also appears to fix the random disconnect problems users have reported on the Apple discussion boards. This update is for the internal usb modem only."
I think this feature has a bug that is playing up with the modem. I confirmed something that I had noticed before. Under my powerbook I see additional options under the modem tab. Things like what to do with incoming calls. This option is not shown on my quicksilver (which dials up fine). They are both apple internal modems, but my TiBook's one has these v.92 options. This is the only difference between computers that dial up fine for me, and computers that don't. Theres no way that is a coincidence.
I'm not sure how to proceed, but this does seem like the probable cause. Please post if you have similar issues, and if you see this AppleModemOnHold app running after you attempt to dial. I see no mention of this being fixed in the 10.2.1 update, so if your effected, post here.