ethersurfer,
To expand on what ProfTech said with an example.
SPX-> X_InboundCallRoute:
{(<**2>(51455551111|x.5145552222|x.5145553333)):aa($1)},{ph}
Explanation:
These are the various numbers which you want to reach the AA. If you hang up before the OBi answers, the ($1) will return the call to the last number that called (you). This is useful for cell plans with unlimited incoming minutes or avoiding a long distance charge. The <**2> is optional. This forces the call over the SP2, otherwise it will use the primary line which is set up.