asterisk users - Dec 2009 - iaxmodem Disconnect time and ISDN Service

Hi,

does anybody know how I can make this two configuration-settings with
Asterisk-iaxmodem for ourtgoing faxes with Hylafax on an ISDN-line?

1. disconnect-time after dialing without an answer. (is now 30 seconds, but it
must be higher)

2. isdn-service set to "3,1 kHz Audio", (is now "speech")

But I do not found this settings and I think this are default settings.
Helpful is in which configuration file this must be set and what are the
parameters.

Best regards
Christian