OFF-TOPIC - ISDN and 56k modem users

[Kinetix]

Has anyone ever used an eicon diva card for a dial-up server??
I have setup such a server using a DIVA 4BRI card in a Redhat box with 
mgetty 1.1.33 and pppd-2.4.3
Everything worked OK for the modem users. The dial-up server sent a 
NAS-Port-Type = Async to the radius server
But when I tried with ISDN users I saw that the NAS-Port-Type that the 
dial-up server sent to radius was Async again
Has anyone any idea on how to make pppd send the correct type of 
NAS-Port-Type to the radius server?