The Time to Service (TTS) feature improves the time required to bring an IP endpoint into service by reducing the amount of required signaling for a telephone to reach the in-service state. Once a telephone is registered, TTS keeps the registration persistent for a relatively long Time to Live (hours) regardless of TCP connection failure, network outages, or even restarts of the endpoint. This significantly reduces the number of times that IP telephones need to re-register with Communication Manager due to outages. As a result, the TTS feature improves system availability after a network outage.

There are two functions in TTS that improves the availability of IP endpoints. One function is that the IP Endpoint Time-To-Service feature changes the way IP endpoints register with their gatekeeper, reducing the time to come into service. In the current Communication Manager architecture, there are two activities to bring the IP endpoints into service. The H.323 IP endpoint must register with Communication Manager and then it must establish a TCP socket connection between the server and the endpoint for call signaling. Since all the IP endpoints in a system strive to get into service as quickly as possible after an outage, the main server can be flooded with activity. In a system with a large number of IP endpoints, this flooding leads to delays not only for telephones trying to get into service but also for endpoints already in service trying to make calls.

The TTS separates the timing of the H.323 registration process from the timing of the TCP socket-connection setup process. This decoupling of the steps considerably improves the time for telephones to be in-service.

With TTS, after all the IP telephones within a system register to Communication Manager, the TCP socket is established when the processor occupancy level returns to normal. However, when the main processor occupancy level is high, the TCP socket is established on demand (when users make a first call or when a call needs to be delivered to a user) or via background maintenance. Once the TCP socket is established, the socket remains up for subsequent calls. In addition, with TTS, Communication Manager, rather than the IP endpoint, initiates the establishment of the TCP socket resulting in faster establishment of TCP sockets.

The second function of TTS significantly reduces the number of times that IP endpoints need to reregister with Communication Manager. This feature provides the capability to persist IP endpoint registrations across many network failures and other outages. Currently, whenever TCP sockets are dropped, the IP endpoints must reregister. With TTS, IP endpoints do not usually need to reregister for network outages that do not cause the system to failover to an survivable core or remote server. Since most issues with registration delays in the past have been after short network outages, this capability dramatically reduces the number of times that an IP endpoint needs to reregister with Communication Manager.

If reregistration is not required, only the re-establishment of the TCP socket is needed, which is also done in an on-demand fashion. Currently, in a call center environment, the agents must always log in again whenever the endpoint becomes unregistered. As a consequence of not requiring reregistrations after most outages, the agents’ log-ins persist and they do not need to log in again.

Note that reregistration is still required for outages that cause the IP endpoints to failover to an survivable server (and then again when they recover back to the main server). In addition, a Communication Manager reset of level 2 (or higher) or a power cycle on the IP endpoints also requires IP endpoints to reregister because the information for the registration is erased under these conditions. For security reasons, IP endpoints also need to reregister with Communication Manager if they have not been able to communicate with Communication Manager over the RAS signaling channel for an extended period of time.