Setting DNS settings using a configuration profile on iOS will break the visual voicemail feature (i.e. voicemails will never appear). This bug affects all third-party DNS providers, not just dns0.eu.

As far as we know, this only affects the following European cellular ISPs:
- Orange (France)

Help us fix this for everyone by asking Apple to investigate this issue. You can easily submit a feedback via their Feedback Assistant. As this seems to be an ISP-specific issue, you could also reach out to your ISP directly regarding this issue.

Workarounds

This issue can be fixed by manually excluding the domain used by the ISP for the visual voicemail feature.

Orange (France)

You can manually exclude dav.orange.fr when generating the configuration profile by appending ?exclude_domains=dav.orange.fr to the download link.