Thanks for including your exact model number!
The offical Boost Answer will be no. Boost will not support activating any device that is not a Boost Branded phone or a Sprint phone that is on the list here; https://www.boostmobile.com/support/faq/phones-devices/activate-a-sprint-phone/
Model SM-900P for the Sprint s5.
What a peculiar device the sm-g900r7 is! Apparently this model # was sold by some small time CDMA carriers like C Spire and nTelos, possibly others. The device is only listed at the Samsung site support page and does not have the specs. Usually I can do a quick interweb search to find out the GSM, CDMA, and LTE bands that a phone device has support for. This is not so for the sm-900r7. Some sites say this is a GSM device and others say CDMA. Well, it is a CDMA device. Does it have GSM support, I dunno. What LTE bands are supported? Again, interweb listings are conflicting. You need to ask Samsung. Phone companies just dont have info on other companies devices.
If you want a phone to work on Boost it MUST support both CDMA listed and at least LTE 25 that Sprints towers that run on;
CDMA 800 MHz ESMR BC10
CDMA 1900 MHz PCS BC1
LTE bands 25, 26, & 41
Do reply if more question.
Let us know if you find out from Samsung what bands the sm-900r7 actually supports.
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