emerge ekiga gives me: [ebuild N ] net-libs/ptlib-2.6.7-r1 USE="alsa asn audio ssl stun v4l video wav -debug -doc -dtmf (-esd) -examples -ffmpeg -ftp -http -ipv6 -jabber -ldap -mail -odbc -oss -pch -qos -remote -sasl -sdl -serial -shmvideo -snmp -soap -socks -static-libs -telnet -tts -vxml -xml -xmlrpc" [ebuild N ] net-libs/opal-3.6.8-r2 USE="audio plugins sip ssl theora video x264 -capi -celt -debug -doc -dtmf -examples -fax -ffmpeg -h224 -h281 -h323 -iax -ilbc -ipv6 -ivr -ixj -java -ldap -lid -sbc -sipim -srtp -static-libs -stats -swig -vpb -vxml -wav -x264-static -xml" [ebuild N ] net-voip/ekiga-3.2.7 USE="libnotify mmx nls shm v4l (-aqua) -avahi -dbus -debug -doc -eds -gconf -gnome -gstreamer -h323 -kde (-kdeenablefinal) -kontact -ldap -static -xcap -xv" [blocks B ] dev-libs/pwlib ("dev-libs/pwlib" is blocking net-libs/ptlib-2.6.7-r1) * Error: The above package list contains packages which cannot be * installed at the same time on the same system. (net-libs/ptlib-2.6.7-r1::gentoo, ebuild scheduled for merge) pulled in by >=net-libs/ptlib-2.6.7[stun,v4l,video,wav,-debug] required by (net-voip/ekiga-3.2.7::gentoo, ebuild scheduled for merge) >=net-libs/ptlib-2.6.6[stun,-debug,audio,ssl,video] required by (net-libs/opal-3.6.8-r2::gentoo, ebuild scheduled for merge)
Seems you're misreading the output: dev-libs/pwlib != net-libs/ptlib in fact, the former is the legacy version of the later, that's why one is blocking the other. Just unmerge dev-libs/pwlib.
