Dual Lines to Keep PSTN Phone Number

A solution to connect both PSTN phone line and SIP phone line to a device,

to keep old PSTN phone number, and add new SIP number to have richer telephony service.

Solution Panorama
At present, there are still many telephony users using the old PSTN telephony service, which has few functions, old system, bad voice quality, high cost. But they cannot cancel this old PSTN number because many of their contacts will call them by this PSTN numbers.

How to upgrade their telephony service with an easy way? Now we launched this solution to solve this pain point with a simple way.

  • How to use?

Our smart fixed phones are with RJ45 and RJ11 ports, for dual lines connection. They can register to IP PBX/IMS by RJ45/Wi-Fi, register to Analog PBX/platform by RJ11 (normal phone line). Then users can get inbound call by both PSTN old number and new SIP number by free, and call out by new SIP number with richer function and lower cost.

In this way, users can keep old PSTN number, as well add new SIP number.

  • Who are the beneficiaries?

The SIP fixed telecom operators, SIP telecom service providers, SIP VNOs, and other SIP telcos can bring and push this solution to SMEs, stores, home users, etc.

Helps SIP fixed telecom operators to increase market share from the current PSTN user market.

Typical Scenarios



  • All IP7/8/9 can connect with analog phone line (RJ11) and IP phone line (RJ45/Wi-Fi).
  • Outbound call: select PSTN or SIP line to call out after dial, or can set a line for outbound call by default. Normally users will set SIP line to call out, because of its cost, features and voice quality.
  • Inbound call: both SIP and PSTN can get inbound call. PSTN line to get previous contacts inbound call only, to save communication cast in the transition period for service upgrades.
SIP Line
Can register to IP PBX/IMS by RJ45 wired or Wi-Fi, compatible with mainstream brands of PBX/voice server, including Broadsoft, Asterisk, Trixbox, Freeswitch, Huawei, Avaya, ZTE, etc.
Can connect with normal analog phone line by RJ11 port. Flexible to get inbound/outbound call by PSTN or SIP.  Keep old PSTN phone number to get inbound call by free.
One device to compatible both PSTN and IP. Users can call out by SIP phone number, with good voice quality and best call plan, keep PSTN number for your contacts to call in by free.
Recommended Models
Some Cases
Canada Office Telephony Upgrade
Deploy IP8 into office for staffs, to connect previous PSTN lines, add new SIP phone lines.
Hotel Reception in Europe
IP8 places an importance role in hotel reception for hotel service upgrade
More cases
Welcome to discuss with us for more cases