Greetings.
On a recent thread, the ELM327 + Torque is mentioned.
Can a cell phone with the proper application in it and no telephony provider service be used/repurposed to monitor/interact the OBD2 ?

 

I use old Android phones without service connections for a number of purposes (guitar tuners, drone controllers, cameras, etc.). Connect to my home WiFi to download apps and updates, but otherwise they just operate as standalone units.
Provided that the Torque app doesn't need a constant live connection, this should be possible,
Not sure if it will be similar if you're considering an iOS unit though.

 

I use old iPhones similarly. I use an old iPhone 4S as a streaming music player plugged into my decades-old stereo. But for reasons I don't understand there are no OBD II devices that work with iPhones via Bluetooth. They all create a Wi-Fi network to which the iPhone connects.

 

I don’t use Torque app but I use UltraGauge Blue app and an old iPod mini with the outdated iOS 9 to monitor my Disco 2. Still works great.

 

I will chime yup they work just fine, I have been using an old Android phone with no service for years.

 

A little late to the party here but I've spent a lot of time using different setups so I'll add what I've learned. Most of the time I use a Scangauge UltraBlue bluetooth dongle (same as Juke) connected to an iPad Mini WITH a cellular plan (more on that later). There are a couple advantages of the Ultrablue, the biggest one is that it simply runs in the background and there's no need to use the interface. You can leave it in the OBD port and forget about it, if you want. It goes into low power mode when the truck isn't running so it won't kill the battery and is a set it and forget solution. I use the iPad for Waze and music 99% of the time I drive the truck, connected to a bluetooth adapter I have wired into the CD input of the factory headunit (a poor man's GROM). Two simultaneous bluetooth connections are supported so there's no issue with the UltraBlue and the bluetooth audio connected at the same time. Despite not actively running the UltraGauge software in months, every ~300 miles the iPad lowers whatever music is playing and beeps to tell me to fill the gas tank, and every 3,000 to change the oil, as well as putting a box on the screen for me to acknowledge. This gives me the confidence that if temps rise above my preset of 205°F the same beeping and visual alert will occur. It's a bit of a leap of faith but it has worked flawlessly for about 6 months so as long the same fuel and oil alerts occur I'm good assuming the overtemp alarm with save me as well. The biggest downside is that the UltraGauge user interface sucks, it's clunky, not intuitive and while it's also a codereader and will let you design your own display screens, I've given up on that part of the game due to the PITA factor. I run a split screen on the iPad with Waze on one side and a music player on the other so I don't bother with UltraGauge. It does not support split screen so there's another bummer, but it runs great in the background.

I also have a generic ELM327 that I use with OBD Fusion for analysis purposes. The ODB Fusion user interface is far superior, beautiful even, and reading codes, graphing data and using it as a multigauge display works great. I would guess it's as good as Torque but have never used that app. I revert back to this setup whenever I do any type of troubleshooting, or want to watch the truck's vitals more closely, specifically for graphing the data in Excel later. The are a few downsides to OBD Fusion and the generic dongle however. The biggest one for me is that OBD Fusion does not have an audible alert, period. This means you have to have the software on screen, and check it, to know if you're entering an overheat scenario. It also supports split screen so I can rotate it in and out with the other apps but if it's not on screen it's not working, and as I mentioned, it's still up to you to check it periodically. Or, in the case of the Disco, continually. Secondly Apple uses a proprietary bluetooth communication protocol and the generic ELM devices don't support it, so if you're using an Apple product you have to get a WiFi dongle, the majority of which WILL kill your battery if you leave them plugged in for a few days without starting the truck. Another nagging problem is that there doesn't seem to be a way to force the iPad to use the cellular connection all. the. time. Once it connects to the ELM327, since it's a WiFi connection the stupid iPad tries to get to the internet over it. Sometimes it will figure it out pretty quickly and tell me "hey, there doesn't seem to be internet there, should we use cellular instead??" Duh. Other times it can be a maddening half-hour before it recognizes the problem and asks if you want to fall back to the cellular connection. I'm not sure how Android will handle this scenario but it's likely more elegant.

Neither of these solutions are perfect but the UltraGauge wins in my book because of the audible alarm. Not only does it provide more accurate temp info than the gauge it the instrument cluster, it shoulders some of the work of actually monitoring the temps with an alarm. The set it and forget it aspect is also a huge plus. It's also the most expensive at about $80, but it will do diagnostic work too if you care to learn how to use it so there is additional value there. There are a few OBD dongles that work with Apple products over bluetooth, PLX Devices makes the Kiwi line for example and they have a few models at various price points but I don't know specifically if they work with Torque or OBD Fusion. I use some of their other products in my other cars and their tech support is pretty good so a simple email will probably get the answer in short order. AFAIK however, none of them have an audible alarm feature, so I haven't investigated further. I did write to OBD Fusion to ask about incorporating audible alarms and they wrote back quickly to say that while they liked the idea, there were no plans to develop that feature set anytime soon.

So, back to your initial question. Old smartphones work great for OBD monitoring with or without an internet connection, and it's not required in the apps I've tried. If you can hotspot your phone, you can get a data connection to to your OBD display which may help with info on any codes you might encounter, however if it's an Apple product that uses a WiFi dongle this will not work since it will not do two WiFi connections at once. Androids are likely more flexible in this department too but I don't have any experience with them. I found that having a dedicated device for any of the aforementioned functions is critical to their usability and success. Asking your actual phone to do all this stuff while still being your phone is a recipe for failure in most scenarios.