Deployment Risks for Competitive Solutions
A significant risk in deploying a PTT system is the added messaging load on the network. CDMA networks are already loaded with telephone calls, data calls and SMS messages. Adding a PTT service will likely increase the network signaling traffic by 4X, since three PTT calls are generally made for every phone call. PTT calls last less time, around 30 seconds, but many more are made than telephone calls.
It is important to look at traffic channel utilization carefully when evaluating PTT. Traffic channel loads are more difficult to calculate given the proprietary nature of most PTT solutions. By design, QChat calls take 40 percent less traffic channel load than full- duplex calls of the same length. QChat’s competitors employ more traffic channel resources in a PTT call than in a full duplex voice call. Operators should measure traffic channel load to determine latency performance when comparing QChat with competing solutions. While many vendors conduct PTT application demos with apparent ease, it is common knowledge that their traffic channels are nailed up during these demos to reduce call set up latency.
Key Factors to Consider
QChat gives a manageable increase in signaling load, but competing solutions will overwhelm the network.
QChat set up latencies are under two seconds. Competing solutions have set up latencies of at least five seconds.
QChat transmission latencies are well under one second and are effectively perceived as instantaneous by the end user. Competing solutions have transmission latencies of two to 10 seconds.