Aleksander, It is good to know that this type of stuff is on your guy's radar. I will look over this work as time permits and see if I can expand on it.
I am still pretty new to working with gObject and GDbus, so I will likely have a plethora of stupid questions, so everyone please bear with me :) Giacinto, I have looked at some of the initial esp api stuff. I just figured out how to disable my modem from auto connecting, so I will actually have some control over the thing. It does sound like there is more I can learn about it though. I will check some resources I have to try and figure out how Verizon would want an MBIM modem to behave. Hopefully I can provide some definitive answers so we can add something that doesn't need to be redone in a year. Thanks for the warm welcome to the community, Jessy Diamond Exum On Sat, Sep 5, 2020 at 1:45 AM Giacinto Cifelli <[email protected]> wrote: > Hello Jessy, > > On Sat, Sep 5, 2020 at 10:11 AM Jessy Exum <[email protected]> > wrote: > >> Hello everyone, I hope this finds you well. >> >> I have been working on getting a product certified with Verizon, but >> failed because my first implementation did not handle their OTA-DM (Over >> the Air Device Management) <http://hosteddocs.ittoolbox.com/CC012507.pdf> >> behavior. This stage of certification relies heavily on creating bearers >> out of PDP context IDs (Verizon handles most of the messy bits in setting >> those contexts for you in the modem). >> >> My current solution is to manually read the PDP contexts off of the >> device with AT+CGDCONT=?, reading out the Verizon mandated PDP context, and >> then asking ModemManager to create a bearer out of that bearer >> configuration (which causes ModemManager to scan the list of contexts and >> find an exact match with the one we just read). This works, but it is >> cumbersome, and I hear that more networks are planning to move to a similar >> process in the future (Sprint already has, though I heard that is a little >> half baked). >> >> *Because of this, I feel it would be worthwhile to allow bearers to be >> created by specifying only a PDP context (and perhaps even an API backed >> way to inspect them).* This would make passing Verizon certification a >> lot less hackey than it currently is. >> >> I am happy to do as much of the work as necessary, but I want to know the >> community's opinion of this base proposal, and make sure anything that is >> built actually solves a problem and will be accepted. >> >> *Brief overview of the OTA-DM procedure >> <http://hosteddocs.ittoolbox.com/CC012507.pdf>:* >> I am not a cellular expert, so please forgive and correct any >> inaccuracies I may let slip in. >> >> For those unfamiliar (I know I was), Verizon has a procedure called >> OTA-DM for automatically determining the APN to use for a SIM card. >> >> Verizon has all compatible modems preloaded with a series of PDP >> contexts. These PDP Contexts are only available when the modem is running >> Verizon firmware (which is triggered when a Verizon SIM card is inserted). >> >> Verizon expects the initial attach bearer will be created from PDP >> context #1. This first bearer is only for notifying Verizon that we have >> attached, and will never pass user traffic. >> >> Once this initial bearer connects, Verizon and the modem talk for a >> while. In this conversation: >> >> 1. The modem reports details about its SIM card to Verizon, >> 2. Verizon checks its database to see if this is the last SIM card it >> saw in this modem, >> 3. if this is not the SIM Verizon expected, Verizon will update the >> modem's PDP contexts to the most up to date settings for this SIM. >> >> To clarify, this process will not happen every time you connect. A modem >> has to connect to Verizon with a different SIM card for Verizon to do this >> process again (flipping between SIMs for each connection would cause this >> process to happen for each connection). >> >> After this process completes, Verizon expects that the modem will connect >> using PDP context #3 for the first data bearer. APNs are not touched by the >> user, only Verizon defined PDP contexts. I found out the hard way that you >> will fail your device certification if you do not connect using the 3rd >> context. >> *END OTA-DM description.* >> >> Any input on if we should allow creation of bearers from PDP context >> numbers to support new cellular network features would be appreciated. >> > > There is an embryo of what you need in the SetInitialEpsBearerSettings(). > For Cinterion modems on VZW networks, the latest MM upstream considers > that the modem will attach with CID#3. CID#1 is not used, but also should > not be overwritten. > I think CID#1 is used internally and transparently. > > Ideally it should be possible to specify only the CID for activating a > PDN, however it is non-portable: modems using MBIM instead of AT commands > don't support the notion of CID at all. > I am not sure how VZW specifies the operations for these modems. I know > that for Cinterion modems AT and MBIM coexist whenever possible, but on the > MBIM_CONNECT there is no CID parameter, only APN (and > username/password/...). > > Best Regards, > Giacinto > > > >
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