Voice over WLAN (VoWLAN) is mobile VoIP, mobile voice communication via radio LANs. VoWLAN can be used as Internet telephony on 802.11-basedWLANs inside buildings and also as VoIP on the Internet via access points.
Behind VoWLAN is the integration of technologies such as VoIP, the Session Initiation Protocol( SIP) and WLANs based on IEEE 802.11n and 802.11e. Whereby 802.11n can be used as the preferred method for LAN access and 802.11e supports quality of service( QoS). In addition, a direct connection to UMTS is possible, thus extending VoWLAN services outside the sphere of influence of the wireless LAN.
Mobile packet-switched voice communication was dominated by proprietary solutions in the early stages and was not addressed on a vendor-independent basis until quality of service was defined in 802.11e, an important criterion for voice communication. It is an interesting alternative to non-IPDigital Enhanced Cordless Telecommunications( DECT).
Since the transmission medium is used simultaneously by several users during radio transmission in WLANs, voice data must be prioritized over other data types in VoWLAN. The R factor has therefore been introduced to evaluate voice quality. This value, specified by the ITU-T in G.107, evaluates the voice quality on the basis of packet loss, jitter and delay times. If the WLANs operate without prioritization, the R factor and thus the voice quality drops rapidly.
Due to the structure of VoIP protocols such as the SIP protocol or H.323, care must be taken to ensure that all accesses are authorized. In addition, data traffic must be encrypted. For this purpose, companies are turning to 802.11i, which performs both functions. VoWLAN telephony is increasingly being used in companies because business calls by employees are often made via smartphones instead of landline telephones.