Quadro4xi The IP PBX with 1 ISDN port, 4 FXS ports and up to 16 IP phones Telephony Voice Features Voice Coding G.711, G.723 (5.3, 6.3 kbit/s), G.726 (16, 24, 32, 40 Kbps), G.729, iLBC (13,33 kbit/s , 15,2 kbit/s) (RFC 3951, ITU-T: G711, G.723.1 Annex A, G.726, G729 Annex A IETF ITU-T Q.23, Q.24, Bellcore GR.506, GR.181 ITU-T G.168-2000, 2002 ETS_300659_1,2,3) NAT traversal (both manually and STUN) VAD, CNG, G.168 echo cancellation   Bandwidth Requirements Per call WAN bandwidth requirements for the following codecs (non-encrypted/VPN encrypted): G.711a/G.711u 20 msec 84 kbps/105 kbps G.726-16 20 msec 37 kbps/59 kbps G.726-24 20 msec 45 kbps/65 kbps G.726-32 20 msec 52 kbps/74 kbps G.726-40 20 msec 60 kbps/80 kbps G.729a 20 msec 29 kbps/49 kbps G.723 30 msec 21 kbps/34 kbps iLBC 30 msec 27 kbps/41 kbps     PBX Features Call block, forward, hold, ID, park, relay, transfer, wait Voice mail Multilevel auto attendant with Interactive Voice Response (IVR) Directory assistance Distinctive ring, hold music, speed dialing Many extensions ring Hunt group Call statistics Do not disturb service Unified messaging 3-way conferencing Hotline service T.38 fax, fax relay and clear channel fax Unified Fax Messaging Busy auto redial Multiple user extensions (up to 70 physical/virtual extensions)