Uhm, are you sure you have the new RIL installed...? The only way to truly verify is radiolog.
You said you put the froyo.user.conf file in a conf folder off the root of the SD - was that conf folder and froyo.user.conf file already there? You just replaced it with the one I posted? Also, the libhtcgeneric-ril.so file is at the root of the SD, no folders? You seem to indicate that's the case... I just want to be positive.
Use the getlogs app if you're unsure and post your logs. Boot up, recreate the issue (make an outbound call, hopefully it causes the failure, then use getlogs to get logs...
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