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DP230Flag for United Kingdom of Great Britain and Northern Ireland

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VoIP calls without IP PBX

Dear Expert, can we make a VoIP call without an IP PBX?

If can, please suggest the best configurations need on switches or IP phones/softphones?

Many thanks!
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VOIP  - Voice over IP    
Has  two minimal needed  types of equipment the Phones (terminals) and PBX(the routers if you like).
( besides a complete IP network infrastructure ;-) )
The SIP protocol allows a Telephone to talk to a PBX...
(BTW this is completely analoge to POTS, there also were terminals (phones) and exchanges (/PBX))

Your phone needs some PBX (yours or from your VOIP providers) to contact another phone either connected to the same PBX or on a different PBX.
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Actually i'm asking of IP calls without any PBX, just like some meeting apps, calling via IP addresses? Example Polycom?
That's not how the SIP protocol works... Like Email there are MUA mail user agents and MTA's mail transfer agents.
MUA talks to MTA.... MTA to MTA  and MTA to MUA.

A Phone is called a SIP User Agent (formally)
A PBX is called SIP Server and is mostly a combination of a Registrar agent, Call Router, A Proxy server possibly a SIP switch.
A user agent is not equipped to search tables and divert traffic etc.

See here:

A PBX is a must whether it is on the premises, hybrid, using analog phones while connecting to the carrier over an IP based.....

you can use skype or cloud based VPN.

it is easier to answer a question to address a solution, then to try and figure out based on what you do not want.

The short answer, yes you can make VOIP calls without an IP PBX.
if you have an analog PBX/phones and your phone provider drops a voicegateway that has Block66 from which they pull the individual lines to feed what you have.
The call will be carried via VOIP.

Polycom has to be receiving data either from a PBX on premises to which it registers or to a cloud PBX ....

Different ringcentral, 8x8, etc. can provide you with a cisco ATA adapter to which you can connect your analog phone and through which you can make calls that will be carried over IP

Some phones have the ability to call each other directly.

For instance Fanvil:

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Many thanks.