Hello!
There is ubuntu with asterisk 1.8.21 configured and used by our office.
I’ve tried to install asterisk-gui, but it didn’t catch up dialplan and sip config. Is there any way to install asterisk-gui or freepbx with using present configuration of asterisk?
No guis has own methods, so if you want a GUI start from scratch. Why do you want a GUI on a working server?
Asterisk GUI is a dead product. If you really want to use a GUI, you need to use FreePBX. As already noted, you will have to start the configuration process over again, from the beginning.
just looking for reports and getting some statistics …
What kind of reports and statistics ?
There are a lot of Web-Applications avalable for gathering different informations from Asterisk-installations - Yoo may google that or use voip-info.org as an entry.
But: without knowing Your specific needs, it’s tricky to give You any specific advice.