How to copy the phone number of the sender of a text message? I'm using a service to report SMS spam via text messages. First step is to forward the text message, and the second step is to send a text message containing the phone number of the spammer.

I achieve the first step by doing a long press on the message itself, then I have a forward menu.
But I can't find a reasonable way to do the second step.

I can see the phone number in various places, but never in a selectable text field. So I have to create a new contact for the spammer, give him a name, tap the phone number  text field, copy, and go back a few steps to create a new text message, then paste the previously copied phone number.

Is there a faster way to do this ?
The message itself reacts to a long press, but the contact bubble on its left reacts to a single tap. Then you can long press on the phone number in the bottom field, and you can copy the phone number from there. 

Edit:

There has been a change in in Android 6.

This answer does not work with the new message application.

With Messengers (as opposed to Hangouts, you can't copy the phone number by tapping the bubble icon.

Instead, tap the three dots in the top right, then find Participants et options (not sure what it is called in english), long press the bubble the label or the bubble of the person you want to copy the phone number from, then copy.

Unfortunately, the actual copy operation behind the menu doesn't seem to be implemented. The phone number is not copied using this operation..

This is inconsistent with the previous way, but it makes more sense in a way, if it worked.