Improved methods and procedures expedite VoIP service turn-up
Given the mass-deployment of voice over Internet protocol (VoIP) services, predictions that this technology will carry the majority of voice traffic within the next three years are close to being realized. Yet, hurdles in the logistics of how these services are deployed still must be overcome. The problems associated with the wide deployment of DSL services tell us that streamlined methods and procedures supported by a simple field test tool can help field technicians turn up new services and troubleshoot problems quickly and efficiently. In most cases, service providers hosting VoIP services handle deployment in three phases: network assessment and prequalification, network equipment install and provisioning, and service turn-up and provisioning. During network assessment and prequalification, the customer's network is evaluated to determine its suitability for carrying VoIP traffic. It is important to assess if the network elements are able to provide specific class-of-service treatment for delay-sensitive voice traffic. Load planning for the new voice traffic helps to accomplish this task. Throughout early deployments and trials, equipment manufacturers' and service providers' network engineers typically carried out this task. However, as commercial service rollouts increase, technicians may be used to baseline networks for service level agreements (SLA) or to upgrade wide area network (WAN) access, routers, and switches. During network equipment installation and provisioning, it is critical to ensure that network elements and network connectivity meet required performance levels. This is accomplished by testing integrated access devices, voice gateways, routers, firewalls, and the physical layer of the WAN links necessary for VoIP services. To perform VoIP application testing during service turn-up and provisioning requires the actual placement of VoIP phones within the enterprise premises. Each endpoint must be tested during installation to validate that all service parameters are met. It is during this phase that any provisioning errors within the network as well as network performance issues affecting quality are identified. Preliminary troubleshooting is conducted on a case-by-case basis to correct or isolate problems. And test records are captured and used as a baseline reference for any future service calls. Today, each phase may be handled by a single work group, a combination of work groups, or partially outsourced to a third party, depending upon the service provider's overall organizational structure. Well-trained data engineers equipped with expensive protocol analyzer test instruments were required to perform service turn-up and provisioning testing. Today, less experienced technicians, armed with new methods and procedures, perform these tasks efficiently and without sacrificing installation quality. During service turn up, the simplest and fastest way to verify connectivity to the signaling gateway, service provisioning, and call quality is for field technicians to place an actual call from the end users' Ethernet phone port or another on-the-premises router port. These test calls are made to: On-the-premises IP phone or plain old telephone system (POTS) Off-site IP phone or POTS phone A provisioned automated test line Another test device manned by a technician or set to auto answer
In addition, placing test calls to these endpoints ensures proper gateway provisioning. When a test call is unsuccessful, signaling decodes can be reviewed for valuable error message content. And PING and trace route analysis can be performed to help sectionalize the problem once connectivity is established or verified. Also, voice quality is measured both subjectively and objectively during these connectivity test calls. Ensuring voice quality The planning process for adding VoIP services along with the ultimate network design are both critical to delivering good-quality voice. CODEC selections determine voice quality at the endpoint (phone). Once the CODEC is selected, it is fixed. However, there are many variables that affect voice quality and must be modified. These include number of users, estimated traffic per user, type of access network infrastructure (frame relay, ATM, xDSL) and class of service treatment (routing priority and buffer size) for delay-sensitive voice traffic. Because latency and packet loss are determined largely by network design, test calls that measure and analyze packet delay, loss, and jitter at the packet level form the foundation of objective VoIP quality measurement. In addition to objective measurements, technicians listening to the call can provide a subjective evaluation. This allows them to associate transient events with packet loss measurements and quickly identify echo problems. The valuable data provided by this analysis, when matched to objective measurements, helps to quickly verify acceptable voice quality. There is a more exhaustive and expensive approach to measuring voice quality that can be implemented using a two-ended test concept. This involves sending test voice segments between test points and performing a "perceptual speech analysis algorithm" analysis to the received voice segments. The attempt to turn subjective analysis (measuring decoded speech) into an objective measurement-although a useful tool for network characterization in a prequalification phase-is expensive, and it may not be effective for field installations. Implementing efficient methods and procedures In the final analysis, the determining factor to VoIP quality resides in the actual methods and procedures (M&Ps) followed by planners, engineers, and field technicians. Placing and receiving test calls in the field must be part of a company's high-quality M&Ps. Additionally, experience has proven that the analysis of test calls at both the packet level and at the subjective level, based upon decoded speech on various test calls, must be a component of standard M&Ps. Portable field instruments with automated processes and preconfigured test scripts ensure that technicians consistently follow VoIP M&Ps, which results in quality installation.