The transaction data is so minimal, if you are using a chip card then I can understand why it's taking so long. Though the ping may have a little to do with it. Do you have the option over wifi?
Did you say if I was using the SIM card? Yes it uses the Vodafone SIM, the transaction is done over GPRS. I just worry sometimes customers do change their mind when a Eftpos problem occurs. My Eftpos machine has no WIFI option nor I can use WIFI on the street. I'll stress my Eftpos machine company coz the SIM is also theirs.