Mobile Voip Dialer

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 ) , Windows phone,Blackberry OS 5 & above , Symbian with the below features . 1) User friendly interface 2 ) supports G723, 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 for android We will need full source code for further upgrades later