Isis, the mobile operator-backed payments venture, is to integrate with American Express’ Serve digital platform.

Separately, it has joined forces with US bank Chase to provide its customers with the option of adding their credit card to the mobile wallet.

Both initiatives will occur with Isis’ nationwide rollout later this year.

Isis and American Express will offer a co-branded account in all the mobile venture’s wallets. Using this joint account, subscribers can pay bills online as well as make P2P transfers to other subscribers.

The joint venture between AT&T, Verizon Wireless and T-Mobile US recently announced its plans to rollout across the US during 2013.

Last year, Isis and Amex agreed that certain Amex cards should appear in the Isis wallet so subscribers can use them to make NFC-based payments at the point-of-sale using their smartphones. Holders of consumer, small business and Serve cards were covered by the agreement.

Under the latest deal, subscribers will also add cash to their Amex Serve account or use an existing bank account, credit, debit or charge card to transfer funds into it.

The current link-up appears, partly at least, a pitch to the unbanked.

“From the palm of your hand, consumers including those without access to traditional bank accounts or credit can have access to everyday financial services. And our combined solution works in today’s retail environment, and in the emerging ‘tap to pay’ point of sale ecosystem,” said Dan Schulman (pictured), group president, enterprise growth, American Express said: