Hello Nikola. You question is kind of confuse.
If you register your quintum to a external gatekeeper, the routing of all the OUTGOING calls is done via the gk.
That means that calls from the PSTN to the I.P. will be routed acording to the routes available to the gk.
On the incoming, from VOIP to PSTN, you should be able to receive calls normally.
Never tried that scenario, but I am willing to give it a try just to learn.
Did you have all the PSTN LAMpattern and LAMreplace fields done????
Now, the other mode of operation of the Quintum is using the “border element”
By using the “border element” , you are not registered to the other gk, but if the other equipment is a Quintum, they will “learn” each other routes.
The same effect of doing the registration, but keep workind independient one from each other
Best luck