If your phone line contracts are soon expiring with an existing carrier, there are many alternative options available depending on the volume of phone calls that need to be accommodated, and what services are provided in your specific geographical location.
If you are a smaller company that does not require a great deal of call volume, individual telephone lines should be sufficient for your business. However, if your call volume dictates that you need as many as 10-12 or more paths for simultaneous conversations, it may be more efficient and economical to have your voice paths delivered by a digital or IP service. If your business requires individual phone numbers (DID) for each person within the company, or if you depend heavily on multi-party conference calls, an alternative to analog telephone lines should be considered. If you have special needs for your Internet bandwidth in addition to your dial tone, there are combination services using digital or IP delivery which would work as well.
Many carriers provide dial tone via digital PRI circuits. A PRI (Primary Rate Interface) will provide you with inbound and/or outbound phone calls and provide as many telephone numbers as you may need for Direct Inward Dialing. This becomes economically advantageous if you are already paying for 12 or more individual phone lines.
If you do not have a high call volume, but still have a need for Direct Inward Dialing phone numbers, SIP Trunks are another delivery option. SIP trunks are able to provide dial tone via IP to your business telephone system, and can customize the amount of call paths to meet your needs. SIP trunks can be a more economical option even if you have fewer than 12 individual phone lines.
As you can see, there are alternatives to basic analog telephone lines that can be very attractive options.