In most cases Infinity 1 is now a self install. If you needed an engineer visit you would have been notified when you order and were given your installation date.
the engineer does not need to come to your home when upgrading to infinity. it is basically plug and play. you just replace your existing hub/router with the new HH5 and that when line is actively should connect without any further assistance
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you can use the existing rj11 modem cable but you need to use the correct power supply for the HH5