Ultra Mobile Paygo(或T-Mobile)的WIFI CALLING开不起来了，怎么解决 2022？

手机端手动改DNS。最简单方便。

在连上WIFI的信号上，添加2条手动DNS

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199.85.126.10

199.85.127.10

或是

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208.54.49.131 depdg.epc.mnc260.mcc310.pub.3gppnetwork.org
208.54.36.3 ss.epdg.epc.mnc260.mcc310.pub.3gppnetwork.org
208.54.35.163 epdg.epc.mnc260.mcc310.pub.3gppnetwork.org
208.54.35.163 ss.epdg.epc.mnc260.mcc310.pub.3gppnetwork.org
208.54.87.3 ss.epdg.epc.geo.mnc260.mcc310.pub.3gppnetwork.org

格式规律是 

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epdg.epc.<服务商 mnc>.<服务商 mcc>.pub.3gppnetwork.org

mnc mcc 号码来自

https://en.wikipedia.org/wiki/Mobile_country_code

例如

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epdg.epc.mnc260.mcc310.pub.3gppnetwork.org for MNC260 MCC310 (T-Mobile USA)

wifi calling

UDP 500,4500

TCP 143