HT831 - Analogue house phone and Office IP phone integration


Hi total Noob here so please bear with,

I have a office at the bottom of my garden. It has a Snom 320 phone all setup and running with a company called VoIPfone. Don’t let that fool you that I know anything much about VoIP.

I would like to connect the analogue phone in the house to office so that I can answer calls to the house and also call the house or it call me eg: Lunch is ready!"

I was thinking that a HT831 would fit the bill.

The FXO port would connect to the BT phone line and the FXS port to the phone handset in the house.

1: As far as the house is concerned can I make the FXO port transparent to the FXS port such that the analoge phone behaves as it did before introducing the HT831?

Have a second account set up on the Office phone connecting me to the HT831. I have no voice server of any kind so I guess that would be a peer-to-peer connection?

2: Be able to answer incomming calls to the house from the office
3: Be able to call the phone in the house
4: Use the phone in the house to call the garden office.

Loads of questions I know but does the idea fly or am I using a sledge hammer to crack a nut.




It is possible but:
SNOM can work peer to peer on extra line ?
Can it call via IP ? (1 is set to FXO port and second to FXS).
Incoming call will only ring house X times then it will be forwarded to Office (no way back).
Home will ring auto to you, so they will need to forced to use extra code to reach PSTN.

It can be very hard to set as you need prepare IP calls but i think it is possible to do.

If you not afraid to pay little more then Instead of HT813 use UCM6202 and you can do whatever you need much easier.
Add PSTN to UCM -> Use FXS for home, use Ext for snom.
You can also prepare intercom/announcement center which allow you to receive “message” that will be played without pickup phone (need check if snom support it). Code for lunch and it play on all devices (not on FXS !)
You can also control that phone will not ring night. You can use it as main system for your office (welcome message etc)

Buy WP820 to have phone all time :stuck_out_tongue: (OPTIONAL).



Thankyou are there any example resources I could look at?

I belive the Snom can do peer to peer and it can call ip addresses


So I have found the HT502 HT503 Peer to Peer example and have applied the settings described to the FXS & FXO ports. For both ports I set the SIP server address to

I can now use the analogue phone and dial normally, it dials out on the PSTN line. Once the call is established it seems to miss the first second or so of speech but is then fine?

Incoming calls ring the analogue phone and can be answered in the normal way.

So that is the first part of the puzzle now to introduce the Snom handset?


Ok so now I can get the Snom to direct dial the HT831 so we are getting there.

What I can’t do is get the analogue phone to dial the Snom


Sip server is 2 side IP not (IP snom phone with port for dedicated line)
Now if you make anything call from analog it will go to Snom.
If you want use analogue line then you need use prefix first (it is set on Basic page afair).
In alternative you can change dial plan to something like this:
ZZZ - any number you want use to dial snom (best is something which is not part of any other number you will dial from analog to PSTN)
L: -> use landline instead of SIP.
{ZZZ, L:x+)

I cannot check this but this work with 503 so it should also work here.
When you take ZZZ it should ring to SNOM, while other number will use PSTN.