Perhaps another possibility, if you have an unused SPx you could setup another registered voip account there and you could fork the incoming Line call to both your undelayed destination without a delay and also fork the call to this new destination with a delay and then not include ph in the inbound routing.
You could get a free CallCentric account and call it with a sip uri.
Edit: Not a good idea. Tried testing it and had problems. Probably need to use both Spx configured as sip to accomplish, one to send, other to receive.