Is it Islamically permissible to talk to my fiancée over the phone?

Talking to your fiancée on the phone is permissible when both parties trust one another and the parents agree to the marriage and have no objections. 
It is acceptable for them to speak to one another discussing matters of life that concern them and the phone conversation should not go beyond what is essential.The conversations should not involve anything that may provoke desire or cause intimate temptation.
The duration of this non-marriage engagement should not be prolonged unless there are necessary reasons for the delay.