HD Voice with AMR-WB
Experience wideband audio that captures the full richness of the human voice — from 50 Hz all the way up to 7 kHz — for calls that sound like the person is in the room.
What is AMR-WB?
AMR-WB (Adaptive Multi-Rate Wideband) is an audio codec standardised by 3GPP and widely adopted for HD voice in cellular and VoIP networks. Unlike the legacy G.711 narrowband codec — which tops out at 3.4 kHz and produces the classic “telephone” sound — AMR-WB extends the audio bandwidth to 7 kHz. The result is cleaner consonants, more natural vowels, and dramatically reduced listener fatigue during long conversations. Free World Dialup supports AMR-WB on calls between compatible endpoints, letting you take full advantage of your modern SIP hardware or softphone.
What you need for HD-capable calling
- A SIP device or softphone that supports AMR-WB
- AMR-WB codec enabled in your device settings
- AMR-WB set as the highest-priority codec in your codec list
- An activated Free World Dialup account
- HD voice support on the other end of the call
When HD voice is available
HD voice automatically activates when both parties to a call advertise AMR-WB in their SDP offer and your FWD account is active. No special dial prefix or manual toggle is required — the codec negotiation happens transparently during call setup. If the remote party does not support AMR-WB, the call falls back gracefully to a supported narrowband codec so the call still connects.
HD voice quality depends on network conditions and the capabilities of both endpoints. Free World Dialup does not transcode between wideband and narrowband codecs — both sides must natively support AMR-WB for HD voice to be active.