I can share with you what we've been learning from the last couple of months at InSTEDD trying to get a project working with a local telco in India. I don't have sources to support my claims, and my understanding may be wrong - but it's all I have for now ¯\_(ツ)_/¯
It seems that Indian regulations require telcos to terminate their SIP trunks in Indian territory. So you _should be able_ to get a SIP trunk working, but you would have to run your own Verboice in-country. We have been allowed to run it on Amazon's AWS datacenter in Mumbai, at least.
Verboice's wiki has a page on Installing your own server. We're also maintaining Docker containers of the app - they are not 100% supported yet, but we're using them and they seem to work. We're lacking a proper setup guide for running Verboice on Docker, but you can probably draw inspiration from this notes on how to setup Surveda, which are *totally a work in progress* but may be better than nothing.
Are you based in India? We have not been able to contact TRAI (the telecom regulatory body there), so if you can get in touch with them, you may be able to help us - would you mind dropping me a line?
Hope this info helps you, and feel free to ask any further questions you may have.