From the Ziper mobile app you click the QR icon and the screen then switches to “QR scan mode” where it can capture the image generated by the VoIP provider. Once captured, Zoiper retrieves all account data and provisions itself.

Zoiper explains, "Until now, automated provisioning for mobile devices was a challenge for ISPs. Conventionally, vast lists of VoIP providers were offered so that the users had to choose theirs. However, this did not take care of users having to manually enter their account details while VoIP providers had to deal with cumbersome account management and support processes to allow customers use their service."

I'll add that many IT personnel don't want their users to have full knowledge of the SIP credentials since they could "steal" corporate minutes by using those SIP credentials on a home-based IP phone device. Of course QR codes are not really encrypted so a knowledgeable enough user could still pull out the SIP credentials from the QR code. Still, security by obscurity helps a little.

Nevertheless, the main point of the QR code feature in Zoiper Mobil is to save the customers time. One tap will take care of server details, codec configuration and account credentials input.

I registered with their website to try and see if I could generate a QR code myself that would auto-provision with our customer premise PBX, but it appears registering with Zoiper Branding Manager merely results in a scheduled sales call from them. They are obviously targeting hosted PBX service providers and ITSPs, so that makes sense to have interaction with a Zoiper sales team member to assist in QR code generation. Still, they should offer a QR generator on their website to allow IT staff to generate QR codes themselves that works with their app. Perhaps they charge per QR code generated to track licenses. If that's the case, they should allow at least one QR code to be generated just to try it out.

Update:
I just tried it out and it doesn't store username & password (SIP credentials) within the QR code. You have to manually enter them. The QR code does store other info like the hostname/SIP server, outbound proxy, proxy port, codecs supported, registration expiration, STUN setting, and a few other settings. After scanning the QR code I created I had to enter in my SIP username and password and then it registered. Pretty cool. Though I think I'd like to see them allow storing of SIP credentials within the QR code. But then you would have to send your SIP username and password to Zoiper, which is a security risk whenever you give a 3rd party access to your SIP credentials.