As I live in an area with no GPRS signal, I routinely divert by Blackberry so that all calls are forwarded to my landline, which has its own answerphone attached to it. Although this works fine if I am not on the landline, if I am on the landline when a call to my Blackberry is diverted, the caller simply receives an engaged tone, i.e. it wont then divert to either the landline's answerphone or the Blackberry's voicemail. BT, who provide the landline, tell me that his is down to the Blackberry, not the landline, yet I dont seem to have a settling on my Blackberry that will cater for this. Any ideas please?

What code are you using to divert the calls? When I do an "unconditional forward" from one of my GSM phones (unconditional forward from "number 1" to "number 2"), if the call is not picked up (busy or Ring/No answer), it goes to voicemail on phone "number 2."

Have you considered subscribing to a voicemail service from your landline provider rather than using an answering machine at your residence?

If you have Call-Waiting feature, then you caller will be put on queue, waiting for you to pick up the call on the landline. If you don't have call-waiting, then the caller will hear a busy signal. I don't think there's an option for the cellphone line to recover the call if the forwarding number is busy or unreachable.

You don't need GPRS to receive calls, GPRS is used for data transmission. Phone calls are carried by cell signals . . . looks like you may benefit from UMA (wi-fi) service, if available from your provider.

The BB cannot backtrack to the VM on the BB account. Once forwarded to a land line , unless the LL has VM from the provider ( not a voip service ) all the caller will get is a tone indicating the line is busy. As suggested above, you need to get a VM on the LL. The BB is working correct.

I do this also if going to an area that the BB service is bad. Always works