Plugging in conference code numbers for a call can be annoying. On an iPhone, you can put the conference code in after in dial-in number. You add a PAUSE in between by holding down the # key. You can also be more clever with IVR systems by plugging in a 3 second WAIT by holding down the * key. Here’s some more ideas on how to use these tricks. For some other phone tricks, check out this short talk from David Pogue.