It is able to receive calls but when I dial a number, it doesn't call out or sound is too low.
If you hear dial tone, but can't dial out. Please follow below to debug:
Case 1: After dialing, dial tone stop but won't make call: You need enter 10 digits (including area code) or press # to make call.
Case 2: After dialing, dial tone won't go away: For some older model landline phone, it requires more power to operate. Please follow below link to download our desktop PC utility to update firmware and change the "off hook power" to high pr stronger (see below picture). Also, change MIC volume to higher value if remote party can't hear clearly www.cell2jack.com/update4