The invention relates to an instantaneous messaging system for mobile terminals comprising one or several instantaneous messaging servers (S1, S2) able to deliver instantaneous messaging services to mobile terminals (TA, TB1, TC1, TD1, TB2, TE2, TF2) connected to said servers and of which the users (A, B1, C1, D1, B2, E2, F2) have opened an instantaneous messaging session, and a virtual presence server (100) independent of the existing instantaneous messaging servers (S1, S2), said virtual presence server being connected to at least one mobile client terminal (TA) and to at least one of the existing messaging servers (S1, S2), wherein said virtual presence server (100) comprises means to automatically manage an instantaneous messaging session in place of said user (A), said means of management being activated when the connection between said mobile client terminal (TA) and said virtual presence server is cut off.
The invention also relates to a method to automatically manage a session in a messaging system for mobile terminals.