Which are the acceptable Patterns that can be used in a Dial Plan?

The correct choice is based on the accepted pattern for dialing plans in telecommunication systems. The +E.164 pattern is the international telephone numbering plan that ensures a standard format for dialed numbers worldwide. E.164 numbers can include a country code, national destination code, and the subscriber number, adhering to specific formatting that ensures consistency in dialing protocols across different regions and networks.

Using E.164 format facilitates seamless communication, especially in global contexts, as it clearly defines the structure of phone numbers and can be universally recognized by various telecommunication systems. This standardized approach is essential for ensuring interoperability between different systems and devices in a VoIP and calling environment such as Webex Calling.

In contrast, while RTP Domain and SIP URI Domain refer to specific aspects of transport protocols and addressing within VoIP communications, they do not represent dialing patterns. Similarly, +E.168 may refer to an alternative dialing pattern but is not widely recognized or utilized in standard telecommunication practices, making it less acceptable for conventional dial plans compared to E.164.