Voicemail setting grayed out, can't change

[Android Central Question]

Hi,
I've Tmobile galaxy s6 egde plus unlocked phone. I bought it from my friend and have benn using it since last 3 years. I used the simple mobile carrier for three years and i think they use the same number for voicemail. But now, i switched to lyca mobile carrier and their voicemail number is different. I tried to change it through voicemail setting but it's not letting me do that. I've a andriod version 7.0. Please help me out because everytime I've to dial the voicemail number to check if i get a voicemail from anyone or not.
Regards

 

[djrakowski]

That's an issue with T-Mobile firmware and it's been that way as long as I've been a subscriber to their service. They won't let you update voicemail settings, unfortunately.

 

[repapips]

Just install T-Mobile Visual Voicemail from Play Store. Hope, this helps.