Sms Gateway pannel

We are a bulk sms resseller company, we work with windows applications that connect to a gateway server by smpp or html post and send sms. Our clients send sms by our software but now we need a sms gateway online since a lot of them dont use windows or just prefer working with the browser. The gateway should really be a simple thing to do, we provide the HTML commands from the gateway and you just have to make us a PHP if possible with ajax app that can: allow users to add their contacts by a TXT file, remove dups and edit their contact lists. most of them should just be simple plain text files with one number per line. allow people to add lists with or without country prefix (if the file does not contain the prefix they add it when loading the list and the server stores it properly) and the simple part, send one sms or bulk to their lists. The admin backoffice also should do really simple tasks like add users and edit them and set each user their credit limit. If possible the website should be easily translated, we intend you to make it fully on english and we will use it in Portuguese and english. Resuming, this is a really simple task and we will probably ask the winning bidder for more jobs in the near future like upgrading the website security and some possible bugfixes. we can talk by gtalk or msn and get it done asap. also if you can make it work under a joomla component or other CMS we are interested as long as it is really safe and the admin pannels are properly protected.