I have a router with OpenWrt installed (orange pi zero with expansion card). I put an external USB modem with a phone SIM card and i configure it to provide an internet connection to the router (it's for a rural localization).
Would it be possible to connect some kind of external phone to make phone calls through OpenWrt?
if you'd have a VoIP service, then yes.
In other cases Skype , Hangouts, Facebook etc works OoTB.
USB modems generally don't support phone calls. Also the carrier plans sold for modems don't allow phone calls (Every SIM has a phone number, but actually calling it is blocked.)
As for using a smartphone as a modem, I don't think that phones have any built in API to make phone calls through the USB port. Maybe an app could do that.
Texting used to be possible with AT commands on a dumb phone, never looked at it on a smartphone.
But i want to do the call using the phone SIM card installed on the router, with any software/package on openwrt that do that operation.
i have for calls and data on that sim, and i want to use it with an external phone connected to the router.
is it posible?
No. It is impossible.
As already said, not possible, but you can always make voice calls at the same time as you use the phone for internet access.
Imposible? Sure.
I understand i can install an Asterisk package for that and redirect it with an USB router donggle.
I saw a that package is on openWrt too.
And for the SIM, I know exist the asterisk plugin “asterisk chan dongle” that redirect the calls to a USB 3G router.
But i was never configure an asterisk, i was have it on the last work but i dont configure it.
OK, have you configured it?