Bonjour,
I'm no LDAP expert, so what follows may be stupid. I'm OK with this,
but I'd prefer receiving pointers to make my mind clearer.
Looking at your network capture, I see the search you're doing has its
baseObject set to "msisdn=9800002868;dc=MSISDN,dc=C-NTDB". Is the
semicolon intentional?
Looking at RFC4514, chapter 3 "Parsing a String Back to a
Distinguished Name", a COMMA separates the RDN elements, and a SEMI
(semicolon, U+003B) must be escaped.
My guess is this semicolon is an error and should be a comma instead.