Size VoLTE load: Erlangs, concurrent QCI-1 bearers, busy-hour call attempts and the bearer bandwidth required.
One Erlang is one call continuously in progress, so the Erlang total is also the average concurrent call count and therefore the number of QCI-1 dedicated bearers in use. Dividing the call-seconds by the average duration recovers the attempt rate that the signalling plane has to absorb. QCI-1 bearers are admission-controlled per cell and licensed per session in the core, so both the concurrent count and the attempt rate gate how many voice users a network can actually carry.
VoLTE Capacity
Erlangs = VoLTE subscribers × busy-hour Erlangs per subscriber; BHCA = Erlangs × 3600 ÷ AHT; bandwidth = concurrent calls × bearer rate.
Erlangs = VoLTE subscribers × busy-hour Erlangs per subscriber; BHCA = Erlangs × 3600 ÷ AHT; bandwidth = concurrent calls × bearer rate. One Erlang is one call continuously in progress, so the Erlang total is also the average concurrent call count and therefore the number of QCI-1 dedicated bearers in use. Dividing the call-seconds by the average duration recovers the attempt rate that the signalling plane has to absorb.
QCI-1 bearers are admission-controlled per cell and licensed per session in the core, so both the concurrent count and the attempt rate gate how many voice users a network can actually carry.
This calculator takes 5 inputs: Subscribers on the network, VoLTE penetration, Busy-hour traffic per subscriber, Average call duration, Voice bearer rate on the wire. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.