SPA2102 Loop Resistance

Unanswered Question
Jun 22nd, 2010


Could anyone tell me what the maximum loop resistance for the SPA2102 is and also if it uses a ringing SLIC or a conventional SLIC?

I want to connect a phone over 2km of copper (24AWG) and wanted to know if the 2102 could handle this.



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Alberto Montilla Wed, 06/23/2010 - 03:54

Dear Craig;

It is a normal SLIC. The SPA2102 will not be able to handle such long distance. You would need a line extender for this purpose.


craig.lawrie Wed, 06/23/2010 - 20:50

Hi Alberto,

Thanks for your response.

Do you know if there is an actual maximum loop resistance documented anywhere for that product.  When we were using the SPA2002 from Sipura, I have a vague memory of them publishing that information.  I don't know if Linksys/Cisco have changed the hardware much since acquiring the IP from Sipura.

When we did some testing here with 470 ohms in each line leg to simulate about 7.5 kilometers of line resistance (assuming 0.64 square mm x-section wire), the SPA2002 operated correctly with our phone (we make roadside help phones).  Of course, using resistors we didn't simulate the frequency dependent components of a cable but they should not have too much effect at voice frequencies.

Some of your other devices quote a maximum of 600 ohms including the terminal equipment which would still almost get to 2km with our phone (approx 300 to 350 ohms loop) over 0.64mm copper.

If you could come up with a number for the resistance I'd be most appreciative.



Alberto Montilla Wed, 06/30/2010 - 10:02

Dear Craig;

Not documented. What I can say is that the SLIC (not product) claims to support 2000 ft with standard load. As I said, this is a non supported configuration.



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