Voip to voip, possible?

I have a private freepbx server on my pc at home, im in thailand, currently i got gsm goip linked to the server and forwarding calls to zoiper app on my phone which registered extension of my voip server, im unhappy with the quality, theres a delay in speech that i cant stand, is it possible to get a local thai voip service that i could link to my freepbx and forward calls to it and then forward to my thai mobile line, that way nothing is wireless, except call forward from the thai voip to my cellphone, which i assume will be in high quality. Is this way possible?

Completely possible. You basically want to call forwarding your mobile number to your VoIP number which will then call your extension on your softphone client.

However, the Internet speeds are also going to play a part in this. So while it may not be “wireless” poor Internet speeds will cause voice quality issues as well.

hmm maybe i wasnt clear.
i got my gsm mobile number back in israel
its in the gsm gateway which linked to freepbx , everycall i get to the gsm mobile number is being forwarded to the extension in freepbx, basically i need to skip freepbx and ask the thai voip provider for trunk details so it connects to it and then forwarded to my thai mobile number ?

Then surely if you want to “skip asterisk” ask the “voip provider”, no?

The delay won’t change because no matter who services Zoiper, (your PBX or Thai VoIP),
the calls still have to go somehow from Israel to Thailand and that causes the latency (delay) you are describing.