The company that Angela works for has deployed a Voice over IP (VoIP) environment that uses SIP. What threat is the most likely issue for their phone calls?

Angela’s company has deployed a version of Session Initiation Protocol (SIP) that doesn’t use Transport Layer Security (TLS) to maintain confidentiality. She should switch to a SIP Secure (SIPS) implementation to protect the confidentiality of phone conversations. Vishing, or voice phishing; war dialing, which attempts to map all numbers for phone service, typically to find modems; and denial of service are all less likely on a VoIP network, although they could occur.