Branded Mobile SIP Client Android/ I OS,Blackberry,Symbian /VOIP

SAME for client: I am looking for an experienced Mobile application developer who can develop Branded Mobile SIP Client for the Android Platforms 2.1 and higher ( Works both on Phones and Tablets ) , I OS ( works on iphone , ipad , ipod Touch ) , Blackberry OS 5 & above , Symbian with the below features . 1) User friendly interface 2 ) supports G729, G711 U & A codec , Make and receive Calls 3 ) Works behind NAT / Firewall or on private IP . Most Important 4 ) VPN Tunnel for Voip Blocked countries 5 ) Should be 4 G Ready , besides 3 G , Wifi , Wimax 6 ) Balance Display 7 ) 3 party Conference , Should be able to revive GSM call when on voip call . 8 ) Standard features , like mute , speaker , call Recording , Redial ,Phone Book (Synchronize with Phone Address Book) , Local signaling (Dial tone, busy, ring back, etc.) , Silence Suppression , Echo Cancellation , Registration Timeout , website URL , signup link We will prefer guys who already have developed same / or worked on csipsimple and can provide branding on existing source code We will need full source code for further upgrades later Developers who have already worked on same project please bid . DONOT OVER BID , we have strict upper limit of 800 $ ,off course lower is better :) .