Cameroon expect Liverpool defender Joel Matip, West Brom's Allan Nyom and Schalke's Eric Maxim Choupo-Moting to arrive at their Africa Cup of Nations training camp on Tuesday.
The trio are among eight Cameroon players to be called up but refuse to play at the tournament, which starts in Gabon on 14 January.
They could be banned from club football during the competition.
Bournemouth striker Benik Afobe has also withdrawn from DR Congo's squad.
"We have three players who are due to arrive, notably Allan Nyom and Joel Matip. The third player is Eric Maxim Choupo-Moting," said team manager Alphonse Tchami.