Issues with contacts sync, Viber duplicates, group texting, MMS attachments, and voicemail – are these related?

Mudita Products
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Hi everyone,

I’m aware there are a few posts out there addressing some of these issues individually. Still, I want to start a new thread because I believe these problems are related, and I’d appreciate a consolidated discussion. I’m genuinely grateful for any help — I really want to continue using the Kompakt.

A bit of background:

I’m one of those US customers on Visible by Verizon who had the SIM card activated in an iPhone and, after disabling iMessage, inserted the newly activated SIM into the Kompakt (forum recommendation). Everything worked just fine besides the issues I describe below. I’m currently switching to Tello by T-Mobile and will be testing how messaging and voicemail work on that network.

I should also mention that I’m one of those folks who can’t handle more than one phone. I need a single device for both work and personal life, which means reliable messaging (including group texts and the ability to view attachments) and voicemail capabilities are essential for me.

The issues/questions:

  1. Contacts sync – one-way only? I’ve tried several approaches here. First, I tested multiple third-party contact apps paired with DAVx⁵, and most recently I used an app specifically designed to sync contacts from my Proton account. In all cases, the phone would accept incoming contacts and allow me to write data locally, but it simply won’t sync changes back to the cloud. Any additions or edits made on the Kompakt stay on the device and don’t propagate to Proton. I recently posted about this on the forum, and I appreciated feedback. Since then, has anyone found a working two-way CardDAV setup, or is this a known limitation that’s being addressed? I tested Fossify Contacts as well, and the same issue persisted.

  2. Viber duplicating contacts in the native app: I installed Viber, which I only use for communication. After installation, many of my Viber contacts appeared to have been unintentionally moved into the native contacts app, resulting in numerous duplicates. Has anyone experienced a similar issue with Viber or other messaging apps writing contacts into the native address book?

  3. Desktop companion duplicate removal not working: The Mudita desktop companion has a built-in function to remove duplicate contacts, but it’s not recognizing the duplicates that Viber created. Is this tool looking for exact field matches? Are there known limitations to what it can detect?

  4. Deleting Viber removed the duplicates. After I uninstalled Viber, the duplicates seemed to disappear on their own, which I find quite strange. Does anyone have insight into why an app uninstall would clean up contacts it had added? Could the phone be treating these as temporary or app-scoped contacts that are removed alongside the app?

  5. Group texts not reliable. For group messaging on the Kompakt, I’ve enabled the “Single MMS group chat” option that sends an MMS to a group of people in a single group conversation. While I can send messages to a group successfully, I don’t receive replies that display as a group thread — individual replies come through separately, which breaks the conversation flow. On a positive note, I can now receive messages sent from a group chat (which wasn’t the case initially), so there’s been some improvement. Still, the inconsistent group thread behavior makes managing group conversations difficult. Is this a known issue with the messaging app, and are there settings or alternative apps that improve group messaging reliability?

  6. Can’t view images attached in messages (MMS): I’m unable to view images that are sent as attachments in text messages. Is MMS image rendering supported on the Kompakt, and if so, are there specific APN or network settings required for it to work properly?

  7. Can’t retrieve voicemail: I haven’t been able to retrieve voicemail at all. I’m planning to test this again on Tello by T-Mobile, but in the meantime — is visual voicemail or traditional voicemail retrieval expected to work on the Kompakt? A friend who attempted to leave a voicemail told me that my mailbox was full. While I had a few voicemails saved on my iPhone that I moved from, I don’t recall the mailbox being full. Are there any steps I can take to address this? Would a move to a different carrier fix this automatically?

All this to say, these issues collectively make it difficult to rely on the Kompakt as my sole phone for work and personal use. I’m hoping some of you may have insights, workarounds, or at least confirmation that fixes are on the roadmap. I’ve come a long way and really want to make this work.

Thank you!

Zvony

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Yes. Make sure that your APN settings include the MMS guidance from your carrier.

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Thanks, Kirk. How can I ensure that my APN settings include the MMS guidance from my carrier? Can I access those settings on Kompakt?

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Search the Interwebs for the name of your carrier along with “APN settings”. @urszula can tell you how to access the APN settings on your Kompakt. (I won’t have one again until v1.6.0 at the earliest.)

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Hi @zyny Thank you for taking the time to describe everything so clearly. We understand why reliable messaging, contacts, and voicemail are essential if Mudita Kompakt is your only phone.

Before going through the individual points, could you please confirm that your Kompakt is running the latest software version, MuditaOS K 1.5.0?

Since you mentioned moving from Visible to Tello, it would also be helpful to know whether you are keeping the same phone number. Although you disabled iMessage on your iPhone, please make sure the number has been fully deregistered from iMessage. If the number was ever connected to Google Messages or another RCS service, it should also be deregistered from RCS. Messages routed through either service may not reach Kompakt as standard SMS or MMS.

To address your questions one by one:

  1. Contacts synchronization

I’ve asked our team about this because I am not familiar with DavX5 and I’m not sure how that works on Kompakt. I’m waiting for the team to help me understand what is happening in your case.

  1. Viber contacts appearing as duplicates

Some communication apps make their own contact entries visible through Android’s contact system. These may look like duplicated native contacts even though they are being provided dynamically by the third-party app.

We have limited control over how Viber accesses, displays, or shares contact information on Kompakt, so it is difficult to determine the exact cause without further investigation.

  1. Mudita Center not detecting the duplicates

If the additional entries were being displayed through Viber rather than permanently stored as native contacts, Mudita Center may not have recognized them as ordinary duplicate records. The duplicate-removal function can only act on contact records it can access and identify as duplicates.

  1. Duplicates disappearing after uninstalling Viber

This behavior supports the possibility that the additional entries belonged to Viber’s account or contact layer. I am not familiar with this communication app, so I would have to ask for some help regarding this issue.

  1. Group messages arriving as separate conversations

Group messaging in the US relies on MMS and can be affected by the carrier, APN configuration, the sender’s messaging service, and whether the phone number is still registered with iMessage or RCS.

Once your Tello service is active, please test group messaging again after:

  • Fully deregistering the number from iMessage and, if applicable, RCS
  • Confirming that mobile data and MMS are enabled
  • Checking that the correct Tello APN is active
  • Restarting the phone after the new SIM and APN settings are configured

If replies continue arriving as separate conversations after these checks, please let us know whether this happens with every group and whether all participants are using iPhones, Android phones, or a mixture of both.

  1. MMS image attachments

Mudita Kompakt supports receiving MMS attachments, but MMS content download must be enabled in the messaging settings. Mobile data must also be available because MMS generally uses the carrier’s mobile data connection, even when Wi-Fi is connected.

After switching to Tello, please also check the carrier’s official APN settings. An incorrect or incomplete MMS APN can prevent images and group messages from downloading.

  1. Voicemail access

Mudita Kompakt does not currently provide direct voicemail notifications. Improvements to voicemail handling, including voicemail notifications for US customers, are included in our public roadmap for the upcoming update.

Traditional carrier voicemail should still be accessible by calling the mailbox. On Tello, you can:

  • Call your own 10-digit Tello number from your device OR
  • Call your Tello number from another phone, press ***** when the greeting begins, and enter your password

Tello provides full setup and access instructions in its voicemail guide.

I’m not sure if your Visible voicemails will transfer automatically to Tello because voicemail is stored by the carrier, not on the SIM or Kompakt. The “mailbox full” message was therefore likely related to your Visible voicemail account. Once the Tello number is active, you will need to initialize and manage its separate mailbox. Voicemail is handled by the carrier, and not the device/phone.

Please let us know your installed MuditaOS K version and how the messaging tests go once the move to Tello is complete. That will help us separate carrier or account-routing issues from behavior that may need further investigation on Kompakt.

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Hi Urszula,

Thank you for your detailed and thoughtful response. I appreciate the time you and the Mudita team took to address each of my concerns so thoroughly.

Here’s an update on where things stand:

Confirmed Information:

  • Software Version: MuditaOS K 1.5.0 (confirmed)

  • Carrier: Switched to Tello (T-Mobile network) about one week ago

  • Phone Number: Same number retained from Visible

What’s Now Working:

  • Voicemail setup completed successfully

  • Receiving images in text messages

  • Sending group texts with “Single MMS group chat” setting enabled

  • “Download MMS content” enabled

  • iMessage deregistration completed (iMessage was used on the previous provider only, never since I switched to Tello on Mudita Kompakt)

APN Configuration: As you suggested, I configured the following Tello APN settings:

Remaining Issue: The primary concern persists: I still can’t receive replies in group texts. When others reply to a group conversation, their messages arrive as separate individual threads rather than within the original group chat. This happens across different group participants.

Questions for Further Troubleshooting:

  1. Given that MMS receiving and group messaging sending work correctly, could this point to a specific APN configuration nuance or a device-side parsing issue?

  2. Would you recommend testing with a group composed entirely of Android users versus mixed iPhone/Android participants to isolate carrier routing differences? My work colleagues are mainly iPhone users, which is the group I’m not getting replies from in my group messages.

  3. Are there any additional logs or diagnostic outputs from the MuditaKompakt you could share with your engineering team to investigate group reply handling?

DavX5

Thank you again for reaching out to your team about the DavX5 contact synchronization issue—I truly appreciate you taking the time to look into it. In the meantime, do you have any additional troubleshooting suggestions I could try on my end? Again, the issue I’m having is that manually entered or edited contacts in native or third-party contacts apps aren’t syncing to the cloud (calendars work just fine).

Thank you again for your continued support. I look forward to your guidance on next steps for resolving the group reply issue.

Zvony

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Are you opening your DAVx5 app on your Kompakt and tapping the synchronize pushbutton on its home page after you edit contacts on your Kompakt? If not, then try that!

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I would, now, encourage you to contact our tech support. They will guide you through the process of sending logs. This way they can see what’s “happening under the hood.”

You can open a support ticket directly on our website:

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Thanks! Yes, I have tried that many times with several different contact apps. I noticed the same behavior with DavX and the Proton Sync Contacts app I posted about recently.

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Thanks, Urszula. Will the support team have access to this post thread? It may be helpful for them to understand what’s going on before further troubleshooting the issue.

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@zyny you can attach it in the ticket. That would be helpful.