# Software Serial and multiple shields for Arduino Uno

I have a SIM900 GPRS/GSM Shield (details here) and I am looking to stack a GPS shield (such as this one here).

My question is: I believe that they both require software serial, also it says to use software serial on D7 and D8 for both. Is this possible on an Uno?

I am a bit confused at if software serial has to have these two specific pins, or if these are just what is chosen on schematics?

What would be the most effective way to stack these two shields so they don't interfere with each other?

EDIT: Using a gps shield such as this gives the option of

If you need to move the software serial port pins, they can be custom-routed to any other pin by cutting the solder jumpers between pins GPS-RX and D8 and/or GPS-TX and D9.

This isn't entirely clear to me, but am I right in thinking it means I can have multiple software serials on my Uno, just using different pins?

• Ah, so even if I have for example: SIM900 on D7 and D8, Wifi on D5 and D6, GPS on D3 and D4. and set up each of these with their own SoftwareSerial serial1(7, 8); SoftwareSerial serial2(5, 6); SoftwareSerial serial3(3, 4); It still wouldn't work? – Calco Aug 3 '16 at 10:36