Concept

Remembering numbers can be difficult. Remembering a word may be easier. In order to memorize big numbers, I created a way to pronounce them in a leetspeak-like way.

Rules

Each digit is first replaced by its corresponding letter:

0 => O
1 => I
2 => R
3 => E
4 => A
5 => S
6 => G
7 => T
8 => B
9 => P

After the replacement, two additionnal things are done to improved pronounciation:

• Between two consonants, a U is added.

• Between two vowels, a N is added.

Examples/test cases

512431 => SIRANENI
834677081 => BENAGUTUTOBI
3141592 => ENINANISUPUR
1234567890 => IRENASUGUTUBUPO
6164817 => GIGABIT

What's impossible

• Letters and numbers mixed in the same word
• Two successive consonants or two successive vowels
• Letters that are not in the list above
• Other characters

Rules

The goal of this code-golf is to create a 2-way translator for this concept.

• Your program must first undersand by itself if it's letter-to-number or number-to-letter translation.
• It must check for the entry to be properly formed.
• If everything is correct, display the translation.
• Else, display an error message, nothing, return a falsey value or crash the program.

Details

• The input number/string can be entered in whatever format you want (stdin, argument, ...)
• This is code-golf, so shortest answer wins.
• Standard loopholes are forbidden.