"For example /b/ is a phoneme in English. It is realised as [b] in
<scribe>, but as [p] in <*scription> of <subscription>" Jean-Paul G. POTET,

"I don't think so. You're importing a Latin rule neutralising /p/
v. /b/ into English. English gets close with the "b" (I think that's
better than {b}, if we have to avoid <b> lest it embolden the
following text.) However, the "p" is definitely pronounced
differently to the "b", so I don't agree. The best counterexample I
can think of is surnames like 'Hobson' and 'Gibson', to compare
with 'gypsum'." Richard WORDINGHAM, ENGLAND

No. It's not a rule that concerns romance languages, but, apparently all
languages. When a voiced consonant is followed by an unvoiced consonant the
universal reaction is to devoice the former.

For instance in Tagalog, maligsí "agile" is pronounced maliksí, and this is
now the official spelling;
similarly hagdán "ladder, stairs" is actually pronounced hakdán, labsáw
[lap'sao] "melted" etc.