https://www.amazon.co.jp/Grandstream-GRP2604P-IP%E9%9B%BB%E8%A9%B1%E6%A9%9F-6-SIP-%E5%9B%BD%E5%86%85%E6%AD%A3%E8%A6%8F%E5%93%81/dp/B091KV9824/?_encoding=UTF8&pd_rd_w=B8cMb&content-id=amzn1.sym.92b41ba0-4204-4cd0-a14e-446ccb8ded9c%3Aamzn1.symc.68e5a0fb-0798-4a4d-861b-9ece178914b2&pf_rd_p=92b41ba0-4204-4cd0-a14e-446ccb8ded9c&pf_rd_r=YR9JZAGS92D15XWM2ZXH&pd_rd_wg=3ANnU&pd_rd_r=f6aa1602-2245-4e40-99dc-3472de014285&ref_=pd_hp_d_btf_ci_mcx_mr_hp_d
思考の /dev/null
