The prepaid mobile phone services of 120,000 Kogan users are in limbo tonight, after wholesale provider ispONE went into voluntary administration.
As a supplier of Telstra services, ispONE provides wholesale prepaid connections to about 250,000 customers.
Kogan Mobile prepaid users will receive a text from Telstra informing them services are no longer supported, and they will use interim Telstra services.
The 130,000 remaining ispONE users, part of the Medion network sold through Aldi, narrowly avoided the same fate under a deal with Telstra.
For the Kogan users, the contract termination means they cannot recharge their phone and any existing data, call and text balances will expire in 30 days.
"You will not be able to recharge, so if you lose your outbound service, we advise you to transfer your service to another provider immediately," Telstra said on its website.
Telstra said it was also progressively moving Kogan customers to a limited seven-day plan.
"During the 7 Day Plan the service will be limited to 20 voice call minutes and 20 SMS messages to Australian numbers, while data services, international calls and MMS will be excluded," it said in a statement.
"After the 7 Day Plan, and for a period of 6 months, the service will no longer be able to make calls, although it will still receive calls and you'll be able to make emergency 000 calls.
"If the service has not ported out after the 6 month period, the service will be cancelled and the number placed in quarantine."
Kogan customers will need to transfer their mobile number to another provider - a process known as porting - but given the large volume of people transferring, there are expected to be delays.
Telstra has urged Kogan users to be patient.
"There are limits on how many ports the industry can process in addition to normal sales and activation activity," the statement said.
Rival telco Optus is hoping to take advantage of the uncertainty, offering a special deal to affected customers.
"We're hoping to make things better by offering an easy way for you to come to Optus, keep your existing number and continue using your mobile service," Optus's Ben White said.
ispONE's administrators Ferrier Hodgson said ispONE's debt appeared to be about $30 million and there were 20 to 50 creditors.
"An agreement had been entered into for the sale of the fixed-line telephony services, the fixed internet services and the provision of post-paid mobile access," administrator Stewart McCallum said.
"We are currently reviewing the terms of the sale agreement with an eye to finalising it and bringing it to completion."
Mr McCallum says those involved are doing everything to minimise inconvenience to customers.
"It's too early to tell exactly how that will play out," he said.
"But what we're aiming for is a situation where those Kogan Mobile customers will be able to use any prepaid amounts that they have sitting on - that they may have paid for."
Ferrier Hodgson said the 50,000 internet users of ispONE will not be affected at this stage.
Brisbane resident and Kogan customer Steven Lowien says he uses his mobile phone for important jobs every day.
"Mobile is my number one form of communication, if it got cut off with no warning it would just be so inconvenient," he told PM.
"I haven't had any communication from Kogan any more, but it seems like the court case has gone through, and yes, we're going to be cut off.
"When I tried to contact Telstra today I had no information from them. I was transferred to the Philippines, the customer service guy was really helpful but he wasn't authorised to give out any information.
"I asked if there was anyone in Telstra I could talk to to get more information on this subject, and he said no.
"He just said they're waiting on a response from the court case. So they had yesterday's news when I rang up."