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POTS hand-off to PBX

Adtran n00b here.  Will be using an Adtran to hand off from a SIP trunk to POTS on a PBX.  From my experience with other hardware manufacturers, this needs to be done with an FXO port, but from what i can tell, the Adtran TA 900's cant do more than a couple FXO lines (I think I saw the 924 can do up to 8 FXOs).  If i need to hand off, say 16 POTS to a PBX, what Adtran device can I use to get 16 FXO ports on? or will FXS ports work?

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Honored Contributor
Honored Contributor

Re: POTS hand-off to PBX

FXS is what you want. It acts like a phone line. FXO is what is on the PBX for CO lines. It acts like a phone. You should be fine.

FXS on Adtran:

Provides battery

Provides dialtone

Provides ringing

Expects loop closure (or ground-start)

Expects DTMF


Expects battery

Expects dialtone

Expects ringing

Provides loop closure (or ground-start)

Provides DTMF

When dealing with analog lines, it's important that the Adtran and the PBX be connected to earth ground, preferably at the same point.