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New Member

Fax and Modem Over IP

Is it successful and reliable to deploy the fax and modem over IP in production? Does it stable enough to replace the PSTN connection?

Do delay and packet drops in the network affect so much for fax and modem traffic?

How about to implement fax and modem over IP via microwave link?


Re: Fax and Modem Over IP

I've had good success with fax over IP in production. An error free network with minimal loss and jitter is key. Excessive delay, packet loss and jitter will definitely affect this type of traffic. I have no experience with fax/modem traffic over a microwave link, but I would highly doubt that this would work with any consistency.

Hope this helps. If so, please rate the post.


New Member

Re: Fax and Modem Over IP

Thank you for your explanation. I agree with your statement.

I implement fax/ POS modem over VoIP with the CUCM. There are a lot of error and packet loss at the microwave link going to PGW.

We had a test with POS Credit Card machine, sometimes it works perfectly and sometimes it dosn't. We got error "no response" and "communication error" from called server.

Can you explain why this happen to this kind of network?

Re: Fax and Modem Over IP

This is likely due to the errors and packet loss that you mentioned. You might check with the carrier regarding these problems. Also, check you configuration to make sure that there is not a misconfiguration causing slips, etc.


New Member

Re: Fax and Modem Over IP

i have read in the article in the web. here is the link

1) Can you comment about implementing POS modem over IP is not reliable and workable.

2) What the fine tune need to do most to successfully deploy the POS over IP?

3) We had using Linksys SPA2102 ATA for the POS machine to be connected to the CUCM. Is it recommended brand ATA for impementing the POS?

4) What is your experience implementing the POS modem? To CUCM or any Media gateway or IP PABX?