SIP Soft Phone App Development

Hi, I'm looking for someone to build a sip soft phone that has no dialer for outbound calls. It will only receive incoming calls. It will need to have my logo/ branding on it and can be downloaded on the Google app store..preferably for both Android and iPhone... (Budget: £20 - £250 GBP, Jobs: Android, Android App Development, iOS Development, iPhone, Mobile App Development, Mobile Development, SIP, VoIP)