second dialing tonesecondary dial tone二次: secondary; quadratic拨号音: dial tone; trunk tone一次拨号音: dodi:direct outward dialing one二次拨号: two-stage dialing拨号音: dial signal; dialling tone; dt dial tone; dt dialing tone下载手机词典可随时随地查词查翻译关注微信公众号：chachacidian，回复:二次拨号音，即可在微信中查询翻译
