Mystery signal: 877.875 MHz (Solved)

While using my SDRPlay RSP, I noticed a weird signal centered on 877.5 MHz.
Here is a picture of HDSDR receiving the signal on 5 MHz bandwidth:

It is 2.55 MHz wide, and I haven't seen anything like this on www.sigidwiki.com. It could be some sort of cell phone tower signal

(Update 1/08/2016) I asked about this on the GNURadio mailing list and they say it's either IS-95 or CDMA 2000, both old cell phone signals. They also say it's actually 2 signals beside each other.