Preconfigured Siphone for iphone android an WebRTC to integrate with Asterisk PBX

We would like to offer our students a free multiplatform PRECONFIGURED SIP softphone preferebly using PJSIP sipstack and should use OPUS as the prefered voice codec. This will be used to communicate with our company ASTERISK pbx. Its crucial that all platforms be tested for good quality audio with asterisk. Platforms should be: iPhone, Android and a WebRTC which will make calls (SIP protocol) to our call center for free. Actual programming in some cases is MINIMAL (android -> use opensource Csipsimple -> only change to have preconfigured SIP account in apk install file) We would like for open source software (sip phones) to be used to save time and money. On most platforms there are ready made softphones that fill our riqueirments and only a preconfiguration of a sip account needs to be made). Examples of softphones using PJSIP: [login to view URL] Android -> [login to view URL] we currently use this and are quite satisfied and it would need no modifications, just preconfigure a sip account. [login to view URL] iPhone/iPad -> [login to view URL] WebRTC - open source SIP [login to view URL] [login to view URL] [login to view URL] safari -> [login to view URL] The integration will be with an asterisk pbx and I will need to test each platform for compatibility. The use of OPUS is a VERY HIGH PRIORITY so we can offer exceptional voice quality.