While VoIP phones offer far more features and better clarity than legacy phones, troubleshooting VoIP phones requires voice and networking skills. It isn’t necessary to be CCNP certified. However, understanding the fundamentals of networking is very helpful. I’d recommend Cisco Certified Entry Networking Technician (CCENT) or Microsoft Networking Fundamentals (MTA) for anyone entering telecommunications.
When it comes to VoIP phones, just because you hear a dial tone in the handset, it doesn’t mean you have a PBX (cloud or on-prem) connection.
