Help with replacing Isp router/modem

[NickForcer]

My Isp gave me a router/modem which is not that reliable and I can't really use solely my aftermarket one because it has to have VOIP (or the phones at home won't work at all which I don't really use but it's nice to have) and something called hybrid connection (which basically accepts a Sim card inside and combines 4g network with dsl*).

Possible solution:
What I though of doing Is use the Isp router as a modem and route the internet through my router and let it handle the wifi and ethernet connections.
Is that a good idea?

I Would really prefer an alternative though which does not include my isp router/modem.

Are there any aftermarket routers/modems that accept Sim cards and have voip?

Is there any other modem router combinations I could try?

Could I use something like this? Or is there any better one? https://www.asus.com/Networking/DSL-AC52U/

Any help will be gladly accepted. Thanks!

(*I currently live on an island with unstable dsl internet so 4g helps alot..)

 

[tommyducker19]

I'd have a look at the Draytek range. Something like the model below.

https://www.box.co.uk/Draytek-Vigor-2760-ADSLVDSL-Router_1971644.html

Draytek aren't cheap but do have the extra features you are looking for. Business tend to use them.