Mobile operator O2 is to replace a key user database that was involved in both of this year's network outages that left angry users unable to receive calls and texts.
The firm will spend 10 million on decommissioning hardware and software installed by Swedish company Ericsson.
This follows an outage earlier this month that left two million customers, mainly in London and the South East, without mobile phone service.
An investigation found the fault to lie with the transition to Ericsson's Centralised User Database, which left user's phones unable to authenticate to the network.
The second outage, unlike the first in July, won't see customers compensated for the loss of service.
The database allows Sim cards to register on and access O2's network.
Derek McManus, chief operating officer at O2 said in a blog post that the company was "not prepared to risk this happening to our customers for a third time" and is "implementing a proven alternative solution."
He said the firm would also be spending an additional 10 million on the change, and will continue to invest 1.5 million a day on building out and improving its network.
McManus said that two network faults in a short space of time was "unsatisfactory".
"We took important steps with our supplier after the outage in July to prevent a similar fault happening again, and while this issue was not on the same scale, it did impact our customers," said McManus.
He added that a new "Service Experience Team" would be set up to improve customer confidence during "this period of unprecedented investment, culminating in the delivery of our 4G service".
He concluded by saying that the company won't rest "until we have cemented the stability of our network and can deliver the level of service customers have come to expect of us over the last ten years."
