Shang fxo gateway provides more feature to work with asterisk.
1.play asterisk ivr with no interuption.
when the Shang received call from co line, it wouldn't conect instantly.instead, it start call to asterisk ivr first,when the ivr ready, it connect the co line. this feature make user feel friendly.
2. pbx voip/pstn inteleged route.
when you make pbx connect to voip/asterisk, how to make voip more stable. Shang could detect the voip quanlity, when voip line failed, it change to pstn line automaticly.
3. pstn caller number transfer.
When pstn call in, the Shang start voip call to the asterisk using pstn caller number instead of gateway number.
4. multy region pstn singal support.
By using MindSpeed technology, it integrated many region's pstn singal.
Why we choose a voip fxo gateway while not a asterisk card.
1. voice process is a realtime task. PC operate system is not a realtime one. Voip gateway use its own dsp to do voice process while asterisk card use PC CPU to do this. Just like the DVD decode, on heavy task, voip gateway hardware will do better. So we sugguest you to use voip gateway on more than 4 phone line system.
2. Asterisk PC+ voip gateway model, it is easy to expand to over 100 user. In this scale, you can not plug so many card into one PC.
3. There are many analog voip gateway producer, the price is cheap, especially for Shang fxs.
How Shang backup voip with the PSTN line
Shang 4s4o owned 4 fxo and 4 fxs ports. When you work in backup mode, 4 fxs ports connect to pbx trunk line, 4 fxo ports connect to CO line. User start a voip call from fxs port, When a voip call failed, Shang will automatically dial on the pstn line through fxo port. The end user use the gateway like it was on voip line. So the voip call quanlity is protected with pstn backup line.
The voip change to pstn condition is: when voip service is unavailable or the power is loose.
It is very difference than lifeline. Lifeline is a n to 1 protection. This is 1:1 protection. Lifeline work only when the power is loose, it has no use when the network is down.