When the phone [was ringing / rang]

Hello, everyone,

In the sentence, “When the phone [was ringing / rang], she was writing a letter to her best friend.",

1. which tense is more suitable? I assume that among the simple past is better than the past continuous, since the past continuous indicates that a longer action in the past was interrupted. The interruption is usually a shorter, temporal action in the simple past.

2. if ‘rang’ is suitable, can the simple past be replaced with the past continuous one in case of ‘while’ in the place of ‘when’? It’s because I have seen no. 2 in the following explanation (I assume the context of no.2 example is a different case with the original one);

‘When’ has four meanings:

1. interruption—He was holding his newborn baby when you called. ("called" ["rang up"] — short duration² )
2. same time—He was holding his newborn baby when (or while) he was talking on the phone. ("was talking" —longer duration³)
. . .
https://www.grammar-quizzes.com/adv_whenwhile.html

Would hope to hear,

RGDS