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Walkthrough Wednesdays

Same POTs FXS Dial-Peers in a SIP VG224 to the CUBE

Hi All,

Good day,

I was thinking if it is a good idea to have a VG224 configured with the SIP Protocol to send Outgoing Faxes.

We have already migrated SITEs to be a SIP VoIP calls for all the calls.

The call flow would be like this.

Outgoing Fax

FXO port x2222 --> VG224 --> POT FXO Dial P --> VoIP SIP Dial P --> CUCM Trunk --> CUBE --> Telco

Since the SIP Trunk with the Telco have a lot of bandwidth capacity, I was curios whether having the same extension in the POTS Dial-Peer could allow us to Use like 5 faxes at the same time to send Faxes.

Of course, inbound faxes will be load-balanced among the dial-peers.


Outgoing Faxes (at same time) to Different Destinations.

FXO port x2222 --> VG224 --> (inbound) POT FXO Dial P 2/10 --> VoIP SIP Dial P --> CUCM Trunk --> CUBE --> Telco

FXO port x2222 --> VG224 --> (inbound) POT FXO Dial P 2/11--> VoIP SIP Dial P --> CUCM Trunk --> CUBE --> Telco

FXO port x2222 --> VG224 --> (inbound) POT FXO Dial P 2/12--> VoIP SIP Dial P --> CUCM Trunk --> CUBE --> Telco

FXO port x2222 --> VG224 --> (inbound) POT FXO Dial P 2/13--> VoIP SIP Dial P --> CUCM Trunk --> CUBE --> Telco

It will be something like this

dial-peer voice 200 pots
 destination-pattern 2222
 incoming called-number .
 port 2/14

dial-peer voice 201 pots
 destination-pattern 2222
 incoming called-number .
 port 2/15

dial-peer voice 202 pots
 destination-pattern 2222
 incoming called-number .
 port 2/16

dial-peer voice 203 pots
 destination-pattern 2222
 incoming called-number .
 port 2/17

dial-peer voice300 voip
 destination-pattern 1[2-9]..[2-9]......
 session protocol sipv2
 session target ipv4: (to Call Manager)
 codec g711ulaw
 no vad

I want to think that every call will have a specific session-global ID, and even if it is the same pattern for the POTS Dial-Peer, it would not make any difference because it will be mainly for Outbound Faxes.

What do you Think?

Chris Deren
Hall of Fame Master

First of all the VG224 does not have FXO lines, but FXS, and no the VG224 will not send call to all ports at the same time as there is no concept of shared line appearance on dial-peers, if all of the dial peers are configured with the same preference and the same destination a random one can be selected, but typically the first one configured one is. So in your case the fax to 2222 will go to port 2/14. 

Remember fax tones need to be negatiated between endpoints (fax to fax) so concept of sending the same fax to multiple fax machines is technically impossible, so only one can negotiate the tones.

Thank you for the clarification.

Sorry If I did not explained myself.

I was talking about Outbound Faxes at the same time, but to different destinations.

I have clear that inbound calls going to the VG224-FXS (thank you), they chose to go only by one dial-peer, hence one port.

Hostname(config)#dial-peer hunt ?
  <0-7>  Dial-peer hunting choices, listed in hunting order within each choice:

1 - Longest match in phone number, explicit preference, least recent use.

But, for outbound, this would be the call flow:

Fax --> VG224 --> CUCM -- CUBE --> Telco --> Destiantion 1

Fax --> VG224 --> CUCM -- CUBE --> Telco --> Destiantion 2

Fax --> VG224 --> CUCM -- CUBE --> Telco --> Destiantion 3

But how about outbound Faxes?

Would that work?

The use case for this scenario is for the outgoing faxes to share the same Calling ID.

I this case, I believe the calling ID would be the destination pattern of the dial-peer where the call is coming in (to outside) the vg224.

Also when the remote party want to send a Fax-Back, it pick the least recent machine, it is OK since all the faxes are in the same room.

Outbound faxes from the analog ports will go to CUCM per the dial peer 300 which matches all NANA 11 digit dialing. the dial-peer being matched is going for the inbound leg is going be port specific pots dial peer using the destination-pattern as described here:

You could change that by adding another dial-peer with "incoming called-number ." if you want to but that should not be needed.

Please elaborate on your last question as I am not sure what you mean, any fax can call anywhere that your dial peers allow.

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