ho scaricato i sorgenti ma riprovano l'installazione mi da sempre lo stesso errore

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Configuro hsfmodem (6.03.00lnxt04032800full) ...
Conexant HSF softmodem driver, version 6.03.00lnxt04032800full

If you need license keys, assistance or more information, please go to:
http://www.linuxant.com/

When reporting a problem for the first time, please send
us the file generated by "hsfconfig --dumpdiag".

No pre-built modules for: Debian-testing/unstable linux-2.6.3 i686-SMP

Trying to automatically build the driver modules...
(this requires a C compiler and proper kernel sources to be installed)

ERROR: /lib/modules/2.6.3/build points to a missing directory

lrwxrwxrwx 1 root root 20 Apr 18 16:17 /lib/modules/2.6.3/build -> /usr/src/linux-2.6.3

Please ensure that the kernel-headers or kernel-source package is installed.
dpkg: errore processando hsfmodem (--configure):
il sottoprocesso post-installation script ha restituito un codice di errore 1
Sono occorsi degli errori processando:
hsfmodem
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