Can't text with one specific friend

[calail]

I have a Sumsung s4, and a friend has Samsung S5. Just last week, we can no longer text each other although we've been texting each other for years - and specifically a year on these devices. We are both on Sprint's network.

I've checked both phones - neither has the other listed as SPAM or blocked. Phones are able to call each other, and both receive texts from other people with no problem.

If I text her, my phone acts like the text is sent (no errors) and appears in my sent folder. Same happens on her end - the text appears to send normally with no errors.

Both phones use Google Voice for voicemail messages, and texts are received through GVoice, but not the standard messaging app which is what is preferred for texts (and which works for everyone else).

I've checked and updated all software/firmware on both phones.

I continue to be stumped. Any ideas?

 

[Rukbat]

Use the standard messaging app. Send her a text through Sprint, asking her to do the same. If it doesn't work, contact Sprint. If it does, contact Google. (To determine what's happening, the text has to be traced. We can't. Google can't trace Sprint's texts and Sprint can't trace Google's texts.)