The other day I called a colleague and he answer HELLO on the first ring tone. I perceived it as if it was even less than 2 seconds or so.
Granted the call quality was great. I was amazed and surprised at the same time. Voice over LTE (VoLTE) not only brings in better voice quality. It also results in least amount of call setup time as well compared to other conventional and non-VoLTE related voice solutions. User perception of voice call setup time through VoLTE has resulted in faster connectivity versus conventional solutions.
This results in Call Setup Delay becoming one of the major key performance indicator ( KPI ) in case of VoLTE from end user perspective. Long setup delay can make poor user experience about VoLTE call.
As a performance engineer and optimization engineer, it is important to understand what could be the causes for long call setup delay in LTE, so that optimization can be performed accordingly. Below we will talk about some of the reasons that could cause long call setup time for VoLTE
Call setup time is the time from the moment VoLTE user initiates the call until the user receives notification about the called party being alerted. This call type termed as VoLTE to VoLTE, and call setup time is measured entirely from the UE, which originates the call.
Typical Call Setup Time is 3 to 5 seconds.
In order for VoLTE Optimization engineers and performance engineers to investigate what is causing long call setup time. You can continue to read further. The reasons for long call setup time could possibly be due to any of the following reasons.
Ideally, the shortest VoLTE latency is achieved when both the UEs involved are in RRC Connected state.
Ideally, the longest VoLTE latency is achieved when both the UEs involved are in RRC Idle state. (not connected)
What did you experience as the major causes for longer VoLTE call setup time factors in your market? Please share in the comments below. Thanks 🙂