VoLTE Capacity Calculator
Size VoLTE load: Erlangs, concurrent QCI-1 bearers, busy-hour call attempts and the bearer bandwidth required.
Inputs
Concurrent VoLTE Calls
20,000
Busy-Hour Traffic
20,000Erlangs
Busy-Hour Call Attempts
654,545calls/hour
Voice Bearer Bandwidth per Direction
928.00Mbps
Step by step
Values used
Subscribers on the network = 1,000,000 subscribers; VoLTE penetration = 80 %; Busy-hour traffic per subscriber = 0.0250 Erlangs; Average call duration = 110 seconds; Voice bearer rate on the wire = AMR-WB 23.85k — 46.4 kbps
VoLTE Capacity
Erlangs = VoLTE subscribers × busy-hour Erlangs per subscriber; BHCA = Erlangs × 3600 ÷ AHT; bandwidth = concurrent calls × bearer rate.
Concurrent VoLTE Calls
= 20,000
Busy-Hour Traffic
= 20,000 Erlangs
Busy-Hour Call Attempts
= 654,545 calls/hour
Voice Bearer Bandwidth per Direction
= 928.00 Mbps
How it works
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.
Formula
VoLTE Capacity
Erlangs = VoLTE subscribers × busy-hour Erlangs per subscriber; BHCA = Erlangs × 3600 ÷ AHT; bandwidth = concurrent calls × bearer rate.
- Erlangs
- Average number of calls in progress during the busy hour
- AHT
- Average hold time per call
Frequently Asked Questions
How is VoLTE Capacity calculated?
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.
Why does VoLTE Capacity matter?
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.
What values do I need to enter?
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.