I bought the above mentioned phone on 15 April 2015 from MTN Bafoussam Branch and until today, I've been a prisoner to the phone;I had no choice than use an MTN SIM card in slot 1 of the phone.The worst thing is that I could not use the fast 3G service in slot 1 with SIM cards from the other local service providers as designed by the service provider(MTN). When I go to areas where there is no MTN 3G network, my phone is virtually handicap.
After continuous research on this issue, i got the solution.If you doubt me,then you will never believe me.I have the app and I have the procedure. It has worked with my so shall yours.I can now us Orange and Nexttel in slot 1 of MTN S620.
Contact Njobe Serge Ngala on Facebook or call 677698769 for more details.Thanks.