Telephony and VoIP covers cloud PBX systems, SIP trunking, softphones, contact-centre software and voice APIs. Organisations use it to replace legacy phone systems, to connect offices and home workers, and to build customer service lines and voice features into their own applications.
Calls expose who talks to whom, when and for how long, and recordings and transcripts expose the content. Providers also operate in a regulated sector: public electronic communications services fall within the scope of NIS2, which brings security and incident-reporting duties. Sovereignty depends on where signalling and media are processed, which carriers terminate the calls, and who can access recordings. Phone numbers are a hidden form of lock-in: porting is possible but relies on provider cooperation, and integrations with CRM and contact-centre tools can be hard to rebuild.
In a European option, check where media servers and recordings are hosted, whether recordings can be encrypted or switched off, which carriers and sub-processors are involved and how number porting works. Look for standard SIP support, so that you can combine devices, numbers and providers freely.