Has anyone tried calling 911 with custom ROM

This may be a silly question to ask but an important one. Awhile ago I called 911 and noticed it had a special display picture. This was on my stock android and I was curious what cyanogenmod would look like so I google searched it. By chance I found some articles claiming 911 does not work on some phones running CM. Can anyone confirm they have successfully called 911 using custom ROMs like CM?

Example complaint.

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