One reason that it is “much more difficult” is that not only do the settings in the VoIP box have to be correct and the settings in the VoIP account have to be correct but … because VoIP is a somewhat more advanced network protocol, it has to work hard just to get through the router, which among other things may be doing NAT. That is to say, the settings on the router have to be correct too. (And technically if your ISP is “Big Brother”, the ISP itself may interfere with correct operation. This might particularly apply where you are attempting to use mobile data as your ISP and your mobile network operator isn’t really expecting customers to be using SIP. So in that case there is no router as such but the mobile network operator is causing some of the same problems.)
There are typically a great number of settings in a VoIP box but almost all of them can be ignored (left at factory default). I would estimate that a Grandstream might require between a dozen and two dozen settings in order to “just work” but perhaps it depends on the specific model. (Fairly recently my different make of VoIP box died of old age and I replaced it with a Grandstream.)
My SIP provider, CallCentric. has a web page for configuring various ATA boxes and softphones, including Grandstream, but of course not for Gnome dialer. That got me up and running with the Grandstream very quickly, but the Grandstream device configuration web form had drifted a bit from the CallCentric instruction page, so there was some uncertainty and anxiety. The various softphone apps had drifted much more.
My L5 will register over wifi, but not (AweSIM) mobile data.
It might be a good idea to map out a new method of getting the Gnome dialer working with SIP. Something like:
1.) Purism hires someone who is an expert in SIP protocols to help get SIP working on the Gnome dialer on the Librem 5. This could even be a contract person and not necessarily an employee.
2.) The hired SIP expert works with someone who can be the best person that Purism has when it comes to coding on the Librem 5. Together, they figure out where all of these required settings exist in the Gnome dialer. If nothing like that already exists, then build it. A text based configuration file would be optimal. A SIP expert knows how all of the configurations need to work. Upgrade the Gnome dialer code to work with the configuration file if that feature does not already exist in Gnome dialer. My Google Voice app works well on my Android phone. There must be a way to make SIP work well with T-Mobile, Mint, or AT&T. My Android phone does well with SIP on Mint. So SIP does work rock solid reliably and with no bugs or required work-arounds. It’s just that no one but Google and a few Android App writers have it figured out. So step two is to get it working and to document how a Librem 5 owner can get it working on their own Librem 5 with at least one of the bigger carriers or MVNO operators.
3.) Publish all of the requirements to make it work. Then start working on how the router has to be setup to use SIP at home via WiFi.
This is all just Engineering work, nothing more. If I had had all of the right college courses, then I could make all of these SIP configurations work. It’s no mystery. We just need to find the person who knows how to do it. Numerous SIP landline phone manufacturers have it figured out for the hardware that they sell. If purism can make SIP work on the Librem 5, that will give Purism a good “Plan B” in the event that 5G eventually locks voice communications up so securely that Purism can’t get voice communications working at all after 4G is turned off. At least with data only connections and SIP working, the Librem 5 could survive being shut out of voice communications from the cell phone carriers. If the big carriers start requiring a type of authentication that the Librem 5 can’t provide to get voice communications to work (maybe even from a government mandate), then the Librem 5 will be useless as a phone without a working SIP connection.
If a big enough reward were offered, then we would have SIP working well on the Librem 5 in probably less than two weeks. So the real problem is that no one cares enough to make it work.
I care! And I’m willing to put up some $$ for such a bounty. My ultimate wet dream is a carrier-free communication network that provides reasonably useful voice calls. Take back our communication privacy and independence.
I remember a company named Codeweavers. They probably still exist. They developed versions of the wine software that targeted specific Windows applications. So people could pledge support for their favorite Windows applications, right in the Codeweavers website. As the Codeweavers staff developed support for new Windows applications to run in Linux, they also released new versions of their wine program to support those newly supported Windows programs.
Ms-Office was one of the most commonly nominated software suites where people actually put up money. Sure enough, it didn’t take long until the Codeweavers version of wine supported Ms-Office. I remember paying $39.00, just to purchase the Codeweavers version of wine. It installed in to my Linux PC with no problems (no hacking, no configuration settings, no hunting down any Windows dll files to make it work). All I did was run the specified command from bash. Then I executed the newly installed program and inserted my Ms-Office CD in to the CD drive. The program then ran the Ms-Office installer program from my CD drive, as it installed Ms-Office on to my Linux PC. You could see some Windows-like stuff going on while the Ms-Office CD ran. Then the Office installer stuff would hesitate and you could see things installing from the bash Window. The hybrid install went back and forth, some Microsoft things installing, some Linux things installing, then repeat. A few minutes later the installation process ended, leaving several different Ms-Office icons on my Linux desktop. The Microsoft Office software all ran flawlessly on that Linux box. All of the other Windows programs that I installed in to that Linux distro worked flawlessly also.
Maybe Purism should use this same model to get the Gnome dialer and other apps to run well on the Librem 5 also. I would pledge money to get some apps working on the Librem 5. The most significant part of this method is the part about no hacking being required by the user. You just install it and it just works.
but perhaps it depends on the specific model. (Fairly recently my different make of VoIP box died of old age and I replaced it with a Grandstream.)