PVDM and T1 are different path for VoIP

eemoon used Ask the Experts™
Hi Anyone can confirm the concept? PVDM and T1 are physically different path for VoIP? Thank you
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T1 is the circuit that is used.  

PVDM stands for packet voice DSP module; it is the Cisco product name for the module that provides digital signal processing resources to a system. DSP stands for Digital Signal Processor; it is a generic Industry terminology.

The PVDM is in the router, sometimes directly on the T1 card depending on the WIC or module that is used.

So it depends what you mean by voip.  Many would consider say a cisco phone system to be a voip system because it has all ip phones and all the ip phones call each other using the IP protocol.  However, that same system may have a T1/PRI circuit bringing in voice from the PSTN.  Once that call comes in via the PRI and is processed through the DSP the call is sent from that point via voip to the phone that the call is going to.  

The difference is where the company has a SIP trunk to a SIP provider for PSTN access.  That would be voip all the way to the cloud, whereas the first example is voip in the network and a gateway to connect to the PSTN through traditional connections (i.e. T1 and PVDM technology.)

Hope that helps.


Thank you so much for your reply

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