As we have confirmed that dialling from a different phone network results in the same issue, this would suggest there is something wrong with this number or a specific network. As this falls outside of MyRepublic's network, we can't troubleshoot any further. However, we suggest getting in touch with the person who owns the numbers you can't call and let them know. They may need to check with their own phone supplier to troubleshoot the issue.
If you would like to discuss anything else with us, you can chat with us below.