SIP providers have thousands of local phone numbers ... In addition, when switching service from a landline to a VoIP line, the landline number can often be ported to the SIP line.

To determine the top SIP trunk services of 2025, we evaluated and compared 15 popular providers. Our research found Plivo to be the top choice due to its flexible pricing and wide global coverage ...

Many companies continue to rely on traditional phone systems, including trunk line telephone setups ... The gateway then sends this information to the SIP provider over the internet.