Hello Waruna Haputhanthiri,
I believe the series you are looking for are the SRP520/SRP540 series. Specifically, the SRP526W/SRP527W, the SRP526W-U/SRP527W-U and SRP546W/SRP547W. Here are some links to the Admin guides so you can check each device out personally to see if there are any other features you are interested in and/or wanting.
SRP520 Models Admin Guide:
http://www.cisco.com/en/US/docs/routers/srp520_series/srp521w/administration/srp500_admin.pdf
SRP520-U and SRP540 Models Admin Guide
http://www.cisco.com/en/US/docs/voice_ip_comm/unified_communications/srp540_series/administration/srp500_AG_2567701.pdf
I hope this helps answer your question.
