sudo apt-get install sip-communicator
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.

Since you only requested a single operation it is extremely likely that
the package is simply not installable and a bug report against
that package should be filed.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
  sip-communicator: Depends: alsa-oss but it is not installable
E: Broken packages
________________________________________________________________________________________





deb http://us.archive.ubuntu.com/ubuntu/ gutsy main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy main restricted

## Major bug fix updates produced after the final release of the
## distribution.

deb http://us.archive.ubuntu.com/ubuntu/ gutsy-updates main restricted
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy-updates main restricted

##Universe

deb http://us.archive.ubuntu.com/ubuntu/ gutsy universe
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy universe
deb http://us.archive.ubuntu.com/ubuntu/ gutsy-updates universe
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy-updates universe

## Multiverse

deb http://us.archive.ubuntu.com/ubuntu/ gutsy multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy multiverse
deb http://us.archive.ubuntu.com/ubuntu/ gutsy-updates multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy-updates multiverse

## Backports

deb http://us.archive.ubuntu.com/ubuntu/ gutsy-backports main restricted universe multiverse
deb-src http://us.archive.ubuntu.com/ubuntu/ gutsy-backports main restricted universe multiverse

## Canonical Partner Repository 

deb http://archive.canonical.com/ubuntu gutsy partner
deb-src http://archive.canonical.com/ubuntu gutsy partner
deb http://security.ubuntu.com/ubuntu gutsy-security main restricted
deb-src http://security.ubuntu.com/ubuntu gutsy-security main restricted
deb http://security.ubuntu.com/ubuntu gutsy-security universe
deb-src http://security.ubuntu.com/ubuntu gutsy-security universe
deb http://security.ubuntu.com/ubuntu gutsy-security multiverse
deb-src http://security.ubuntu.com/ubuntu gutsy-security multiverse

## PLF REPOSITORY (Unsupported.  May contain illegal packages.  Use at own risk.)
deb http://packages.medibuntu.org/ gutsy free non-free