No and yes  (please dev correct me if I am wrong)
the voip services the wallet, and the messanger service are all encrypted and decentralized set up on the node system built into the wallet

the viop to landline services are not decentralized( I dont think) because in unless the dev knows how to buypass the systems already in place, I think you need to join a centralized server in order to connect to the system already in place.

so its only the landline phone gateway which is encrypted through the nodes, but not decentralized because of the nature of landline calls.  it is however decentralized on the wallet end.

once again dev please correct me if I am wrong.

BC