Emerging net-voip/sflphone will install only the daemon part of this application (sflphoned). sflphone-client-gnome is not installed, so you can't use the softphone at all. From the README file packed with the source code: sflphone-common: contains the core application code (means sflphoned) sflphone-client-gnome: contains the GTK+ client for SFLphone. (and this is what is missing in Portage). Sources: https://projects.savoirfairelinux.com/attachments/download/2162/sflphone-0.9.13.tar.gz (stable) Hope this can help fixing it.
Is your sflphone emerged with gnome useflag ? If not, likely INVALID. If so, attach build log.
You are right. Gnome use flag was missing. Now emerge correctly builds sflphone-client-gnome. Unfortunately when I try to run it, it says segmentation fault. SFLphone 0.9.8 [stdout] ERROR org.sflphone.gtk - Failed to call register() on instanceProxy: Process /usr/lib/sflphone/sflphoned received signal 6 [stdout] ERROR org.sflphone.gtk - Failed to call get_codec_list() on ConfigurationManager: Process /usr/lib/sflphone/sflphoned received signal 6 Segmentation fault
Created attachment 286099 [details] emerge --info
Try again with 1.0.1 - I am closing this bug as it is invalid.