cheapest 8 port 32 sim gsm gateway

we have stock in bd, so you needn't to worry about the delivery and customs clearance problem.
http://www.ejointech.com/en/product/goipgateway/2012-11-17/56.html
ACOM508G-32 GSM VoIP Gateway

Key features:
Support 8 channels 32 SIM cards and 4 SIM cards per channel rotation using
Support 850/900/1800/1900MHz quad-band GSM network
Support BTS and carrier change and locked
Support IMEI and PIN modify
Support encryption: RC4, VOS and Ejoin private etc, OEM encryption support
SMS receiving/batch sending, AT command compatible
Support USSD balance enquiry
Automatically lock/switch SIM card according to its balance, balance alarm

Basic features:
Support SIP registration and peer-to-peer
Support Hotline, Phone book, Speed dial, Dial Plan
Update firmware by local or internet
Field proven compatible with Asterisk-based softswitches
Single-channel debug for manual calling, directly AT command
LCR automatically route calls
Centralized network management
Caller ID detection and generation
Master and slave SIP server
VLan and QoS support
SIM card hot plug
Calling Statistics
Support customized IVR

Specifications
Network

GSM

Model

ACOM508G-32

Number of Channels

8 channels 32 SIM cards and 4 SIM cards per channel rotation using

Frequency

850/900/1800/1900MHz quad-band network

Call Control Protocols

SIP

Voice CODECs

G.729A, G.723.1, G.711 a/ulaw

Network Protocols

IPv4, TCP, UDP, PPPoE, DHCP, DNS, NAT, Telnet, HTTP, FTP, TFTP

Configuration and Management

·Web-based GUI
·Console, telnet command line
·Centralized network management

Firmware Update

Local file, FTP, TFTP and HTTP

Message Features

SMS batch receiving/sending, AT command compatible

Telephony Features

·Hot-line call
·Dial plan
·Speed dial
·Phone book
·CDR
·White list

Telephony Signaling

·DTMF tone dectection/generation
·DTMF relay: in-band, RFC 2833 and SIP info
·Call forward: unconditional, no answer and busy
·N-way conferencing
·Mobile Number Portability

Voice Quality

·Echo cancellation
·Silence suppression(voice activity detection, comfortable noise generation)
·Adaptive jitter buffer

Number of Ports

·1 WAN 10/100Base-T ethernet(RJ-45 connector)
·1 LAN 10/100Base-T ethernet(RJ-45 connector)
·1 console(RS-11 connector)

LEDs

1 power and 4groups of signal strength and running indicator

Power Supply

100-240VAC, 50 - 60 Hz

Dimensions

•Rack mountable 1U chassis(compatible with 19" Rack)
•Width: 482mm
•Height: 44mm
•Depth: 210mm

Weight

2.5kg

Operating Environment

·Operating temperature: 0 - 50ºC
·Operating humidity: 10 – 90%

Warranty

12 Months