This morning I spent some time in several tests.
In my mind best practice for incoming and outgoing fax with 1 line is as follows:
(Please remember, we are talking about very less incoming fax)
Install Fritz!Fax (while installing procedure take care to disable any firewall on your pc)
After install Fritz!Fax should start without any error messages.
If you get some messages only push ok button. (maybe several times).
Now you should open fax - settings - ISDN and check my settings.
Your local phone has to be replace my "123456" (my number is only fake)
If you got some error messages before, I guess radio button "Fritzbox Internet" is greyed and not pushable.
In this case you have to close setup window (better fritz!fax too) and to call #96*3* to enable capiovertcp (
http://service.avm.de/support/de/skb/FR ... rtet-nicht only availible in german)
Now this should work correct. Otherwise I give you another link.
I aktivated in enhanced settings speech too.
In my envirement I got this:
If Fritz!Fax ist opened, I get Fax inbound and Fax outbound but no phone.
If Fritz!Fax is closed, phone is active.
If you disable dialin in Fritzfax, phone inboundt and fax outbound will work.
Disadvantage in this scenario: Fax sender has to anounce fax before via phone.