Physical dimensions (H×W×D)  | 3.9 x 3.9 x 1 in. (100 × 100 × 28 mm)  | 
Weight  | 4.7 oz (132.1 g)  | 
Hardware  | Interface: Two RJ11 FXS ports, one 10/100 Mbps RJ-45 Ethernet port,  | 
power button: reset and PRT  | 
LED indicators: Power, Network, Phone 1, Phone 2, PRT  | 
Wall mountable  | 
Subscriber Line Interface Circuit (SLIC)  | Ring voltage: 40 to 90 Vpk configurable  | 
Ring frequency accuracy: 1%  | 
Ring waveform: Trapezoidal or sinusoidal  | 
Maximum ringer load: 3 Ringer Equivalence Numbers (RENs)  | 
On-hook voltage (tip and ring): -46 to -56V  | 
Off-hook current: 25mA +/-10%  | 
Terminating impedance: 600 ohm resistive, 900 ohm resistive, or 220   ohm + 820 ohm  | 
120 nF complex impedance  | 
Frequency response: 300 to 3400 Hz  | 
Return loss (600 ohm, 300 to 3400 Hz): up to 26 dB  | 
Idle channel noise: <-65 dBm 0p  | 
Longitudinal balance: 58 dB (typical)  | 
Voice quality Mean Opinion Score (MOS): >4.0  | 
Voice quality jitter: <150ms  | 
Networking  | MAC address  | 
IPv4 only  | 
IPv6 only  | 
IPv4/IPv6 dual stack  | 
Session Initiation Protocol (SIP)  | 
Transmission Control Protocol (TCP)  | 
User Datagram Protocol (UDP)  | 
Real Time Protocol (RTP)  | 
Real Time Control Protocol (RTCP)  | 
HTTP  | 
Secure HTTP (HTTPS)  | 
Trivial File Transfer Protocol (TFTP)  | 
Address Resolution Protocol (ARP)  | 
DNS A and AAAA records  | 
Dynamic Host Configuration Protocol (DHCP) client  | 
Internet Control Message Protocol (ICMP)  | 
Simple Network Time Protocol (SNTP)  | 
Cisco Discovery Protocol (CDP)  | 
Link Layer Discovery Protocol (LLDP)  | 
Quality of Service (QoS)  | IEEE 802.1p/Q (QoS and VLAN tagging)  | 
Differentiated Services (DiffServ) / Type of Service (ToS)  | 
Telephony  | Call forwarding: No answer, busy, and all  | 
Call hold and resume  | 
Caller ID generation (name and number): Bellcore, BT, and European   Telecommunications Standards Institute (ETSI)  | 
Caller ID with name and number  | 
Call pickup and group pickup  | 
Call transfer  | 
Call waiting  | 
Conference  | 
Configurable ring frequency  | 
Country-specific tones and cadences  | 
Disconnect tone  | 
Distinctive ringing: Calling and called number  | 
Forced Authorization Code (FAC)/Client Matter Code (CMC)  | 
Failover and fall back  | 
Flash hook timer  | 
Hook flash event signaling  | 
Hotline and warm line calling  | 
Message Waiting Indicator (MWI) tones  | 
Music on hold  | 
Off-hook warning tone  | 
Polarity control  | 
Redial  | 
Share lines  | 
Speed dial  | 
Tip and ring voltage adjustment setting  | 
Visual Messaging Waiting Indicator (VMWI) using Frequency Shift Keying   (FSK)  | 
Audio  | Codec: G.711 a-law, G.711 μ-law, G.729a, G.729ab  | 
Full duplex audio  | 
Echo cancellation  | 
Voice activity detection  | 
Silence suppression  | 
Comfort noise generation  | 
Adaptive jitter buffer  | 
Frame loss concealment  | 
Adjustable audio frames per packet  | 
Call progress tone generation  | 
Impedance and gain adjustment  | 
Dynamic audio payload  | 
Fax and modem  | Real-time fax over IP via T.38 fax relay (Group 3)  | 
Fax pass-through via G.711 (Group 3)  | 
Fax tone detection and pass-through  | 
Auto negotiation on transmission rate  | 
Provisioning and management  | Central configuration  | 
Interactive Voice Response (IVR)  | 
Automated provisioning and upgrading via HTTP and TFTP  | 
SSH access  | 
Nonintrusive, in-service upgrades  | 
Report generation and event logging  | 
Dedicate PRT button  | 
Support RTP statistics  | 
Syslog (multilevel granularity)  | 
Dual image  | 
Security  | System reset to factory default  | 
Password-protected administrator access authority  | 
Provisioning, configuration, and authentication  | 
HTTPS with factory-installed client certificate  | 
Advanced Encryption Standard (AES) encryption  | 
SIP over Transport Layer Security (TLS) 1.1 and 1.2  | 
Secure (encrypted) calling using Secure RTP (sRTP)  | 
Encrypted TFTP configuration files  | 
Image authentication  | 
Secure boot  | 
Secure Shell (SSH)  | 
Power  | DC input voltage: 5V DC at 2.0A maximum  | 
Power consumption: 5W  | 
Switching type (100 to 240V) automatic  | 
Power adapter: 100 to 240V and 50 to 60 Hz (26 to 34 VA) AC input,   with 6-ft (1.8-m) cord  | 
Reliability  | Mean Time Between Failures (MTBF): 300,000 hours  | 
Operating temperature: 32° to 104°F (0° to 40°C)  | 
Nonoperating temperature: 14° to 140°F (-10° to 60°C)  | 
Humidity: Operating 10% to 90%, noncondensing; nonoperating 10% to   95%, noncondensing  | 
Compliance (regulatory)  | CE markings per directives 2014/30/EU and 2014/35/EU  | 
Compliance (safety)  | UL 60950 Second Edition  | 
CAN/CSA-C22.2 No. 60950 Second Edition  | 
IEC 60950-1:2005 (Second Edition) + A1:2009 + A2:2013 and/or AS/NZS   60950.1:2015  | 
Compliance (EMC)  | AS/NZS CISPR 32:2015 Class B  | 
CISPR 32: 2015 Class B  | 
EN 55032: 2015 Class B  | 
EN 61000-3-2: 2014 Class A  | 
EN 61000-3-3: 2013  | 
EN 55024:2010+A1: 2015  | 
EN 61000-4-2: 2009  | 
EN 61000-4-3: 2006+A1:2008+A2:2010  | 
EN 61000-4-4: 2012  | 
EN 61000-4-5: 2014  | 
EN 61000-4-6: 2014+AC:2015  | 
EN 61000-4-8: 2010  | 
EN 61000-4-11: 2004  | 
FCC Part 15, Subpart B  | 
ANSI C63.4-2014  | 
ICES-003 Issue 6: 2016  | 
ANSI C63.4-2014  | 
VCCI-TECHNICAL REQUIREMENTS (VCCI-CISPR 32: 2016) /  | 
CISPR 32: 2015 class B  |