Automated Attendant (IVR)
Attended Transfer
AutoCLIP
Blind Transfer
Blocklist/Allowlist
Call Back
Call Detail Records (CDR)
Call Forwarding
Call Monitor
Call Parking
Call Pickup
Call Recording
Call Routing
Call Waiting (FXS)
Caller ID
Contacts
Custom Prompt
Dial by Name
DISA
Distinctive Ringtone
DNIS
Do Not Disturb (DND)
Event Center
Email to SMS/SMS to Email
Fax to Email
Paging/Intercom
LDAP
Linkus UC Clients
Linkus Cloud Service*
Mobility Extension
Multi-language System Prompt
Multi-language System Language
Multi-site Interconnect
Music on Hold
One Touch Recording
Queue
PIN List
Phone Provisioning
Real-time Status Monitor
Remote Management
Ring Group
SIP Forking
SLA
Speed Dial
Time Condition
User Portal
User Permission
Voicemail

Models	S20
Hardware Version	V2	V4
Users	20
Max Concurrent Calls	10
Max FXS Ports	4
Max FXO/BRI Ports	4
Max GSM/3G/4G Ports	1
Max 4G Port (Data)	1	0
VoIP Trunks	20
Protocol	SIP (RFC3261), IAX2
Transport Protocol	UDP, TCP, TLS, SRTP
Codec	G711 (alaw/ulaw), G722, G726, G729A, GSM, Speex, ADPCM, iLBC, H263, H263P, H264, MPEG4
DTMF	In-band, RFC4733, RFC2833, SIP INFO
Ethernet Interfaces	2 × 10/100 Mbps
IP Services	Static IP, DHCP, VPN, Firewall, VLAN, DDNS, PPPoE, QoS, Static NAT, STUN
Voicemail	5000 min (expandable)
Firewall	Yes
T.38 Fax	Yes
Hot Standby	Yes
App Center	Linkus, Auto Provisioning, LDAP Server, Conference Panel, VPN Server, Billing App*, Hotel App*, MIKO CTI App, char utile h+ Integration, Zoho Integration, QueueMetrics Integration (the V4 hardware doesn’t support Zoho Integration App, QueueMetrics Integration APP, and MIKO CTI App; Features with the star mark need extra license)
External Storage	TF Card
Power	DC 12V 1A
Size (L x W x H) (cm)	16 x 16 x 3
Weight	0.3 kg
Environment	Operation Range: 0° C to 40° C, 32° F to 104° F; Storage Range: -20° C to 65° C, -4° F to 149° F; Humidity: 10-90% non-condensing
Mounting	Desktop & Wall-mount