Dear Sir,
I can provide you web based dialer solution which will fulfill your requirements. You can set ringing duration, add voip provider and much more as per your requirements.
We've been developing VoIP applications last 12 years. We have extensive experience with Asterisk, FreeSWITCH,, Voip Dialers, VICIdial, Twilio API, freePBX, Ringcentral, Avaya, SIP, OpenSip and call center software.
We have been currently doing a lot of VoIP software based on solution like PBX/ViciDial/GoAutoDial/A2Billing/ringless voicemail /broadcast SMS, voice, email, fax and much more.
Let me know when we can discuss further regarding project. Moreover if you have any query then feel free to ask.
Best regards