Is an IP Phone with a dedicated DHCP server possible?

[Tom101]

Is it possible to configure IP phones with only a dedicated DHCP server, and how would it be set up? Or does it need a router?

Completely new to IP phones. Please see the image i have attached. Thank you. 

[Leo Laohoo]

IP phones are DHCP clients (receive DHCP addresses) and do not have the function (nor the requirements) to be a DHCP server.

Look at the screenshot provided.  Do tell:  What is that machine on the top part of the picture (above the switch)?  

Just a reminder, this is a PT exercise.  Do not "re-invent the wheel".  Do not make it complicated.  Read the instructions provided.  Understand the instructions.  If in doubt, ask the instructor(s) -- This is what they are paid to do.  Another thing, some instructors deliberately put "trick questions" to determine which students are actually "thinking" and which ones are simply copy-n-paste their answers from this forum.  

Some PT instructors do hang around here, y'know.  

[Tom101]

Hi Leo, thanks for your reply. I think you've misunderstood my question. I don't want the IP phone to be a DHCP server. Let me rephrase it, please let me know if i've misunderstood your response. 

What i'm asking is, is it possible to set up an IP phone by using a DHCP server so that the DHCP server gives an ip address to the phone? From what i have seen online (mainly youtube) is that you need a router to achieve this. is that correct/incorrect? 

[Leo Laohoo]

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@Tom101 wrote:

is it possible to set up an IP phone by using a DHCP server so that the DHCP server gives an ip address to the phone?

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Ok, that's a different question. 

The answer is "yes".  Cisco phones operate on a rule called "DHCP Option 150" (TFTP IP address).  

(Darn it, I'm trying to keep this relevant without confusing the heck out of you!)

A fresh-out-of-the-box phone is dumb and stupid.  It does not know anything.  A phone does not have any config.  

How will you be able to roll out hundreds (if not thousands) of phones efficiently if you need to configure each individual phones?  Not scalable.  Cisco's answer is to leverage DHCP Option 150.  The phone boots up, asks the DHCP server for an IP address.  DHCP server hands over the IP address to the phone and then adds the IP address of the TFTP server inside DHCP Option 150.  

(The configuration of the phone resides in the TFTP server.  So the phone "knows" where to pull the config from.)

Phone gets the IP address, processes the TFTP server IP address and then goes over to pull down the config.  Phone starts to work.

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@Tom101 wrote:

From what i have seen online (mainly youtube) is that you need a router to achieve this. is that correct/incorrect? 

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Anything that can perform the role of DHCP server will suffice.  A PC with TFTPd32, for instance, will work.  A router, a switch or even a humble Raspberry Pi.  

[Tom101]

So in the DHCP service option i would need to give the TFTP option an ip address? Would this be an ip address in the phone's vlan pool? 

I have attached a screenshot to help explain. 

[Leo Laohoo]

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@Tom101 wrote:

So in the DHCP service option i would need to give the TFTP option an ip address? Would this be an ip address in the phone's vlan pool? 

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I cannot answer this because I have never used PT before. 

Remember, DHCP Option 150 is a "Cisco thing".  Each individual VoIP manufacturer have their own little process.  

[Tom101]

Ok thanks :).

I have set it up with a TFTP address, and the IP phones are saying 'configuring cm list ip phone'. Not sure what that is.