Is there any 'landline' phone that I can use using a GSM SIM?

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Yes, look for a 4G mobile modem router with a SIM slot and at least one RJ11 telephone port Example: Huawei B315s607 You should try to get

GSM Phone With Sim Card Slot % original price,excellent quality Huawei ETS5623 is a dual mode G3 wireless telephone which adopts Buy the latest collection of phones at SLOT Nigeria Find the best deals on a wide range of devices, from top brands to budget-friendly

sugar bonanza deluxe slot Card Slot 1 nano SIM + 1 nano SIM micro SD More Standby Mode Dual SIM Dual Standby More 2G GSM B2358 More 3G WCDMA B158 More 4G FDD- slot can be used intermittently and shared between several users , the GSM uses eight time slots per carrier frequency If an MS transmits data