The present invention related to a Push to talk Over Cellular (PoC) Server for providing PoC communication services in communications system, the PoC Server being arranged to simultaneously perform a first PoC Session between a first PoC Client and at least a second PoC Client, and at least one second PoC Session between the first PoC Client and at least a third PoC Client in accordance with a priority setting. The Push to talk Over Cellular (PoC) Server is characterized in that it is further arranged to: receive, from said at least second PoC Client, a first information indicating that a user of said at least second PoC Client wants to alert the user of said first PoC Client about relevant Media being shared in said first PoC Session; or receive, from said at least third PoC Client, a second information indicating that a user of said at least third PoC Client wants to alert the user of said first PoC Client about relevant Media being shared in said at least second PoC Session; and if the received information is a notification, forward said received information to said first PoC Client; or if the received information is an override message, change said priority setting for said first and/or said at least second PoC Sessions associated with said first PoC Client in accordance with said override message. The present invention also relates to a method for providing PoC communication services, a mobile terminal comprising a PoC Client and methods thereof, a communications system and a computer program product.