Creating Simulated Telephone Load

Discussion in 'General Electronics Chat' started by bigp58, Apr 4, 2008.

  1. bigp58

    Thread Starter New Member

    Apr 4, 2008
    I am currently having an issue with my corporate voice over ip phone system. We have devices that convert digital to analog signal for fax machines and such. However fire alarm auto dialers do not detect the simulated dial tone from the VOIP conversion devices. I have the parts need to simulated the correct load. But i am unsure how they are to be built.

    The tip is the positive wire on a phone line and the ring is the negative. I know that series means in a row but across them i am not sure how to solder these on my board. Any help is greatly appreciated.

    The fix was to purchase a resistor and capacitor to simulate the load across the tip and ring,

    The recommended parts are:

    - 600 ohm rated minimum half watt resistor
    - 0.47 uf (micro-farad) capacitor (100 volt min), tied in series, across the Tip &Ring, to simulate the load
  2. thingmaker3

    Retired Moderator

    May 16, 2005
  3. bigp58

    Thread Starter New Member

    Apr 4, 2008
    I agree. With vonage or other true VoIP systems those are all valid. In a corporate enviorment the VoIP phones get power from PoE switches that are tied to our generator and UPS battery array and our actual calls go over 3 PRI's. In the 5 years from implementation our phones have never went down. I am just tired of paying verizon and SBC 40 bucks a line for something i can provide for free.
  4. Externet

    AAC Fanatic!

    Nov 29, 2005
    A real telephone line load can be sustituted with a 200 ± 100% ohm resistor . If that applies to your system, is unknown.