Custom a2billing + e-commerce php work

We are looking for someone to implement new features into an existing VOIP platform. Our current system is based on php, mySql, asterisk, and a2billing on CentOS. Once we are happy with the finished product, we may need ongoing work to make edits and add / develop new features. We need the following added on to our current a2billing system: - [login to view URL] integration to accept credit cards / store credit cards. - Recurring billing through a cronjob (more details later) - Extra features / capabilities into a2billing. We have already made these extra features work, we just need it designed/coded in a more professional / visually appeasing way. Details will be given at a later point. - Redesign the a2billing customer portal as to our specifications Skills - Extensive php / mysql knowledge - a2billing or extensive asterisk experience - e-commerce experience. We will be storing credit cards, this needs to be done securely - CSS / design skills to implement new features into current customer portal. Ease of use is important Optional skills (not required) - Linux, especially securing production server would be helpful - Asterisk knowledge to help optimize the server - A2billing experience not required but will be very helpful - SOAP experience also helpful