User's Guide
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HT81x User Guide 
EXPERIENCINGHT81X 
Please visit our website: http://www.grandstream.com to receive the most up- to-date updates on firmware 
releases, additional features, FAQs, documentation and news on new products.   
We encourage you to browse our product related documentation, FAQs and User and Developer Forum 
for  answers  to  your  general  questions.  If  you  have  purchased  our  products  through  a  Grandstream 
Certified Partner or Reseller, please contact them directly for immediate support.    
Our technical support staff is trained and ready to answer all of your questions. Contact a technical support 
member or submit a trouble ticket online to receive in-depth support. 
Thank  you  again  for  purchasing  Grandstream  analogue  telephone  adapter,  itwill  be  sure  to  bring 
convenience to both your business and personal life. 
Compliance 
FCC Notice 
This device complies with part15 of the FCC Rules. Operation is subject to the following two 
conditions: (1) This device may not cause harmful interference, and (2) this device must accept any 
interference received, including interference that may cause undesired operation.   
This equipment has been tested and found to comply with the limits for a Class B digital device, 
pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection 
against harmful interference in a residential installation. This equipment generates, uses and can 
radiate radio frequency energy and, if not installed and used in accordance with the instructions, may 
cause harmful interference to radio communications. However, there is no guarantee that 
interference will not occur in a particular installation. If this equipment does cause harmful 
interference to radio or television reception, which can be determined by turning the equipment off 
and on, the user is encouraged to try to correct the interference by one or more of the following 
measures: 
—Reorient or relocate the receiving antenna. 
—Increase the separation between the equipment and receiver. 
—Connect the equipment into an outlet on a circuit different from that to which the receiver is 
connected. 
—Consult the dealer or an experienced radio/TV technician for help. 
Any changes or modifications not expressly approved by the party responsible for compliance could 
void the user's authority to operate the equipment.     










