Good afternoon, I would like to know if on linux there is an app for call...

I have an integrated 4g modem and I would like to call and receive from the sim card and activate the internet

You have not provided details of where such activity would occur?

Be that as it may--via similar hardware that you describe--we as a family-n-close-friends use Telegram on our PCs or laptops
and WhatsApp on our cell phone or tablets; these calls occur via the WiFi connection of said hardware

However I don't understand, you say that you would like to... "activate the internet"
surely if you have a 4G modem, you already have internet access?

Sorry for the bad english..

I have "Hewlett-Packard MBIM 03F0: 9A1D" and the connection works but I would also like to call..
is it possible?

I don't understand your... "I have "Hewlett-Packard MBIM..."

Essentially HP is a brand of a device while MBIM is a protocol
However to try and answer your question... from your information...
No... as such a modem or router provides the transport from your device to another device
so you need an app--like those I mentioned already--to make calls
whatever app you choose must be installed on your device

> transport involves your ISP and your connection details to provide an internet connection
your HB MBIB sounds like it fits within this purpose
> device involves your PC, tablet, cell phone, etc; not your transport device!

ok...
I tried to ask ...
I have a Hp spectre x2 with a SIM card slot..

so I asked if I could make calls, without whatsapp or telegram...
In this video
https://www.youtube.com/watch?v=auuQA0Q8qpM
kde for mobile
performs what I want

Sorry... again, no!
Your HP device is a laptop; to enable it to make calls you will need an app
and besides my examples.. there are other apps
the Plasma Mobile is an cell phone platform under development,
is still experimental and is only installable on a Nexus device... I think the N5