The transmission and reception of alarm or POS signals over VoIP circuits is not recommended and is not officially supported.
However, we have observed that the following settings work in many cases when using the Cisco SPA 112 Gateway Adapter. Please refer to the basic configuration article for this equipment for further details.
Under the Voice tab, select Line1 or Line2 depending on the alarm connection. Then apply the following settings:
- Network Jitter Level: Very High
- Jitter Buffer Adjustment: No
- Call Waiting Serv: No
- Three Way Call Serv: No
- FAX Enable T38: No
- DTMF Tx Method: InBand
- Preferred Codec: G711a
- Use Pref. Codec Only: Yes
- Silence Supp Enable: No
- Echo Canc Enable: No