Hi Kaushal, libpri is not in CentOS. I think that it is in EPEL. Please see following field of "Repo.". [root at localhost ~]# rpm -q centos-release centos-release-5-6.el5.centos.1 [root at localhost ~]# yum info libpri Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile (snip) Available Packages Name : libpri Arch : i386 Version : 1.4.7 Release : 1.el5 Size : 72 k Repo : epel Summary : An implementation of Primary Rate ISDN URL : http://www.asterisk.org/ License : GPLv2+ Description: libpri is a C implementation of the Primary Rate ISDN specification. : It was based on the Bellcore specification SR-NWT-002343 for National : ISDN. As of May 12, 2001, it has been tested work with NI-2, Nortel : DMS-100, and Lucent 5E Custom protocols on switches from Nortel and : Lucent. Name : libpri Arch : x86_64 Version : 1.4.7 Release : 1.el5 Size : 71 k Repo : epel Summary : An implementation of Primary Rate ISDN URL : http://www.asterisk.org/ License : GPLv2+ Description: libpri is a C implementation of the Primary Rate ISDN specification. : It was based on the Bellcore specification SR-NWT-002343 for National : ISDN. As of May 12, 2001, it has been tested work with NI-2, Nortel : DMS-100, and Lucent 5E Custom protocols on switches from Nortel and : Lucent. Regards, -- ----.----1----.----2----.----3----.----4----.----5----.----6----.----7 Tadashi Jokagi mailto:elf at elf.no-ip.org Twitter: http://bit.ly/a4DzKL Yokukitana III http://poyo.jp/ Yokukita blog http://blog.poyo.jp/ Yokukita wiki http://wiki.poyo.jp/ HotPHPPER News http://news.hotphppher.net/