When I call my wife's phone from my phone, I hear three or four rings through my handset before her ringtone starts. Is there a way to reduce or eliminate this delay? (Yes I have checked the audio file. The sound starts instantly in the file.)
There's quite a bit that goes into placing a call to a mobile phone. Here's an excerpt from the Wikipedia article on GSM services, slightly edited for clarity, which does a good job explaining some of what happens when a call is placed to a GSM cellular phone.
When someone places a call to a mobile phone they dial the telephone number associated with the phone user and the call is routed to the mobile phone operator's Gateway Mobile Switching Centre (MSC). The first job of the Gateway MSC is to determine the current location of the mobile phone in order to connect the call. It does this by consulting the Home Location Register (HLR).
When the HLR receives this query message, it determines whether the call should be routed to another number (called a divert), or if it is to be routed directly to the mobile. If the Home Location Register knows that the phone is roaming in a particular Visited Location Register area, then it will
request a temporary number (called an MSRN) from that VLR. This
number is relayed back to the Gateway MSC, and then used to route the call to the MSC where the called phone is roaming.
When the call arrives at the Visiting MSC, the MSRN is used to determine which of the phones in this area is being called. The MSC pages all the mobile phone masts in the area in order to inform the destination handset that there is an incoming call for it. If the subscriber answers, a speech path is created through the Visiting MSC and Gateway MSC back to the network of the person making the call, and a normal telephone call follows.
All of this and more (depending on the origin of the call, the carriers involved, and how smoothly things are running on that particular day) happens in fractions of seconds. When taken altogether, though, it can create a noticeable delay. That's why it takes so long for your wife's phone to start ringing and that's also why there's not much you can do about it. It's all pretty cool if you think about it.