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.