[wfunction]

Sorry, what's an SIP provider? I've looked it up and still don't understand what it is. Is it a residential service? Can anyone get it? Is it some form of VoIP? Or a classical phone line? I've seen it in multiple places but don't understand what it is or which companies it relates to.

[Symbiote]

It's the open standard for VoIP.

It's used in many places, but mostly offices. An office might have an exchange system, with features like voicemail and routing different types of call over different networks.

I have a personal account which gives cheap international calls, which I added to my android phone. I can receive calls at my SIP address, from anyone on any provider. When I make a call, I'm given the option of using the mobile network directly, or SIP.

Naturally, neither the phone networks not the big tech companies want you to use SIP. They'd rather you used normal calls, or their proprietary system.

[StavrosK]

Can you recommend one that works well? I want one that hopefully provides a Greek DID, I want to be able to make calls from my Android to landlines over my home Internet connection, as you describe, but I haven't managed to find a good (read: cheapish) provider.

[lstamour]

I use voip.ms but many others exist. Anveo, Twilio, Vonage, etc. cheapest might be a service that uses Google, but only for as long as Google offers free calls.

[allannienhuis]

+1 for voip.ms. I've been using them for years - they're inexpensive, lots of features, and service has been great.

[pjc50]

It's telco VOIP. Anyone can get it, e.g. https://www.sipgate.co.uk/basic/

And there are various providers which will let you do 'trunking' into the phone system, so you can have any number of handsets with the same origination number appearing on outgoing caller ID.

[HappyTypist]

Twilio, Plivo, etc.

[taf2]

They are higher level then telco and prevent spoofing