[Asterisk-Users] Ring power on Analog adapters

[Steve Underwood]

mattf wrote:

>Hello,
>
>Ok, I've tried tinkering with the ring voltage (this is an editable variable
>on the Sipure SPA-2000) and I still can't get it to work. I plug a generic
>POTS line in and it works, I plug an analog port from our old Comdial PBX in
>and it works. 
>
>with the sipura adapter I've tried changing the ring voltage in the range
>(20V to 90V) and the frequency from 10Hz to 100Hz both in 5 step increments
>and nothing seems to work.
>
90V, 25Hz would be the best starting point. That is the commonest form 
of ring voltage you will find.

>Do these analog -> SIP VOIP adapters truely supply the 24V that a POTS line
>supplies?
>
A POTS line supplies 48V, not 24V. Its loop current is usually more like 
35mA than 20mA. A number of PBX and CTI line cards supply only 24V (the 
Dialogic station cards, for example) and a number of phones don't work 
properly with them. If your adaptor really supplies 24V, that might be 
the problem.

>Anybody have any ideas why this fax machine won't work with any analog
>adapter I've tried?
>
Note that unles you use A-law or u-law exclusively through the signal 
path, no type of modem will work through a VoIP adaptor.

>Thanks,
>
>MATT---
>
Regards,
Steve