> Changing diversions using the phone's menu system attempts an
> immediate "supplementary services" data session with the
> network. So because networks have absolutely no requirement to
> modify diversion parameters on users handsets, I doubt that a
> specific GSM port number has been allocated to facilitate this.
> If it were possible, technical specification 3GPP 23.040 would
> provide the mechanism (section 9.2.3.24.3 or 9.2.3.24.4).
>
> John

> Such a facility was available on Telstra's PSTN network, although
> never used.

What are you talking about? Everyone uses it