~anteater/mms-stack-bugs#76: 
Cannot send

Status
REPORTED
Submitter
~mrhempman69
Assigned to
No-one
Submitted
1 year, 7 months ago
Updated
1 year, 6 months ago
Labels
docs integration mmsd user support

~mrhempman69 1 year, 7 months ago*

Oops! I did not mean to press submit on that yet....

Cannot send mms. SMS does work! My question for helping me to debug is: Does wwan0 (the modem) require a DHCP lease in order to send the MMS message? I know it requires a data connection - but does your modem usually need an IP address in "ip addr" to send MMS successfully? I'm asking because mine doesn't have one - the modem that I'm using is pretty buggy.

Also... do you have any suggestions on a better way to get error message to debug what the problem could be? I will look later for the obvious ones that might be in a help section.

I'm using bookworm on debian - the ModemManager is debian latest - the mmsd is built from source i think based on the latest release. I realize the instructions say to use Manjaro stuff, but I wanted to quickly go through all the steps first, just to see what the output was going to be. I like the user interface of vmms and that there's also a way to use CLI

The SMS messaging does work! And i like the interface and the cat playing xbox!

~mrhempman69 1 year, 7 months ago

I was able to get things working on Manjaro, but sending photos doesnt work! the groupchat does work though

~mrhempman69 1 year, 7 months ago

It is some kind of null pointer exception, "expected bytes", even though i moved the file to tmp and 777'd it. i tried with png and jpeg

~anteater 1 year, 6 months ago

Thanks for the experience report!

Point-by-point:

Does wwan0 (the modem) require a DHCP lease in order to send the MMS message? I know it requires a data connection - but does your modem usually need an IP address in "ip addr" to send MMS successfully?

The modem does need an IP address (any IP communication does), but this is usually not assigned with DHCP. Instead, the modem negotiates over GSM for an IP, and makes that known to userspace (ModemManager or Ofono) over AT protocol, QMI (the Qualcomm proprietary interface), or less likely some other modem-specific protocol. ModemManager will talk to NetworkManager, and Ofono can integrate via ofonoctl. This should be explained at https://git.sr.ht/~anteater/mms-stack-meta but isn't currently.

In addition, mmsd/mmsd-tng requires the correct "bearer" to be active. A bearer is one specific network connection via the modem, and its APN (Access Point Name) needs to be the right one for communicating with the MMSC. This is technically only necessary on some service providers, but other restrictions (such as only allowing access over the IPv6 address assigned to the handset) may apply. Generally both bearer and other restrictions exist for billing and authentication reasons (for example, many ISPs share IPv4 addresses among many subscribers, but need to know which subscriber is accessing the MMSC so that they cannot spoof sending messages as someone else). The handling of this is one place where mmsd-tng works much better than legacy mmsd. It's probably worth migrating to mmsd-tng, which I should get around to pointing to in the mms-stack-meta overview.

Also... do you have any suggestions on a better way to get error message to debug what the problem could be?

Any output from mmsd/mmsd-tng is worth looking at; it's likely to have the most context for why MMS does not work. You can also see what printed output vgmms gives when attempting to send the MMS, but it's not likely to see the root cause of the problem.

I was able to get things working on Manjaro, but sending photos doesnt work! the groupchat does work though.

Photos and group messages go via the same machinery: they're attachment files uploaded to or downloaded from the MMSC. The only substantial difference may be that images are more likely to hit MMS size limits. Can you check whether sending a smaller image (or receiving images, since any image the MMSC provides as a download has already passed any size limits) works?

It is some kind of null pointer exception, "expected bytes"

Please post the error message itself and what context you can, removing any personally identifying information if desired.

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