External phone ringer for IP-Phone

[otter]

we have multiple IP phones and need an external phone ringer, because of the volume. It's about the model 1603. Does anyone know how we can put there an external phone ringer? Perhaps with an ATA. But the phone should remain an IP phone.
Thanks for the help.

[mskinner]

External ringers are analog devices so you will need analog ports to connect the ringers to Communication Manager. This can be accomplished either through an H.248 gateway or a gateway like the Audiocodes MP114 or MP118. Then depending upon required functionality, you could either use bridged appearances, abridged appearances, terminating extension groups or coverage answer groups.

[otter]

We have no overview of the analog lines.
Another possibility should be to connect the whole thing via LAN and then connect the external ringer with an ATA.
Would that work?