I use three VoIP apps: VoIP.ms (with Groundwire), Talkatone, and TextNow.
I have no problems sending and receiving images in MMS texts with Talkatone and TextNow, but they don’t work with VoIP.ms. Groundwire support says this has to do with the VoIP.ms specs.
Does anybody have any info on this? It seems like a relatively big drawback, isn’t it? Are there plans to upgrade this? Thanks.
I looked at VoIP apps two years ago and found only one that could do MMS, via standard SIP protocol. That was https://www.linphone.org/. However, VoIP.ms does not provide MMS via the SIP protocol. It uses an API. Thus, I had to write some software to bridge the gap, Voip.ms API to Linphone SIP protocol, called MMSGate2.
Sounds interesting, if complicated. 
Does all that run on an iPhone? Also, I have two DIDs which Groundwire supports. Does Linphone also support multiple DIDs?
If it starts getting too complicated I guess I’ll just keep what I have and use VoIP.ms just for calls and plain text messages. I’m not clear on the difference between SMS and MMS. The dashboard says it supports MMS. So maybe it just support a larger number of characters than SMS?
Linphone can support more than one DID. For MMSgate2, you’ll need an extra device for Docker. See the link I gave you for details. There is a Linphone app for iPhone. I tried to make setup of MMSGate2 easy. But you have to decide how much effort you want to put in. I’m the type that puts in the effort up front to make life easy later.
SMS and MMS are very different. MMSGate2 is all about getting text, images, audio and video from/to Linphone and VoIP.ms. It has more features. But you appear to be having issues sending/receiving images. MMSGate2 is intended for that.
I looked over the details. Doesn’t Docker requiring an extra device that’s presumably always working make it sort of impossible to use when, for example, you’re traveling and your devices are mostly turned off on in your backpack?
Correct, MMSgate2 running inside Docker needs to be up and running 24x7. It needs a consistent Internet connection. Normally, that would be any home Internet service. It could be DSL, fiber or a cable service. It should also work with home Internet services that use satellite or mobile services. But I have not tested those.
If you really don’t have a home Internet service, MMSGate2 should work with a VPS. However, I have not tested it. VPS is rather advanced and there will be a monthly fee.
I have fiber optic at home. But if I go on a trip that would take my devices offline while traveling. It seems awkward to require an ongoing connected separate device just to handle that.
I guess the bottom line for me anyway is to just use VoIP.ms as a backup phone and simple text service to handle the Skype number I ported in. The whole original purpose was to not lose my Skype number when Google discontinued that service.
For nice, fuller VoIP experiences I can use TextNow and Talkatone, both of which also receive text messages quicker. VoIP.ms can take up to a minute to receive a text message.
Thanks.
I feel the same. I moved away from a dedicated device to leave home. I use Docker on the router. I use a Linksys WRT3200ACM that the fiber connects to. I put OpenWRT on it. It acts as my home wifi router and MMSgate2. But it may be lots of effort to replace your home router. Easiest may be to just buy a Raspberry Pi. They don’t cost much and use very little power. It just stays at your house, even when you are traveling. MMSGate2 doc has detailed steps to setup a Raspberry Pi.